MailIT.verifyMail is flickering

Expected condition failed: waiting for org.xwiki.test.ui.XWikiWebDriver$$Lambda$965/1622543651@522707f0 (tried for 20 second(s) with 500 milliseconds interval)
Build info: version: '3.141.59', revision: 'e82be7d358', time: '2018-11-14T08:17:03'
System info: host: 'b690f4fbc554', ip: '172.17.0.2', os.name: 'Linux', os.arch: 'amd64', os.version: '4.19.0-13-cloud-amd64', java.version: '1.8.0_282'
Driver info: org.xwiki.test.ui.XWikiWebDriver
Capabilities {acceptInsecureCerts: true, browserName: firefox, browserVersion: 86.0, javascriptEnabled: true, moz:accessibilityChecks: false, moz:buildID: 20210222142601, moz:geckodriverVersion: 0.29.0, moz:headless: false, moz:processID: 285, moz:profile: /tmp/rust_mozprofileSnXuFk, moz:shutdownTimeout: 60000, moz:useNonSpecCompliantPointerOrigin: false, moz:webdriverClick: true, pageLoadStrategy: normal, platform: LINUX, platformName: LINUX, platformVersion: 4.19.0-13-cloud-amd64, rotatable: false, setWindowRect: true, strictFileInteractability: false, timeouts: {implicit: 0, pageLoad: 300000, script: 30000}, unhandledPromptBehavior: ignore, webdriver.remote.sessionid: 941d7a8a-0fa8-4ebc-8922-8f7...}
Session ID: 941d7a8a-0fa8-4ebc-8922-8f7541824a30

org.openqa.selenium.TimeoutException: 
Expected condition failed: waiting for org.xwiki.test.ui.XWikiWebDriver$$Lambda$965/1622543651@522707f0 (tried for 20 second(s) with 500 milliseconds interval)
Build info: version: '3.141.59', revision: 'e82be7d358', time: '2018-11-14T08:17:03'
System info: host: 'b690f4fbc554', ip: '172.17.0.2', os.name: 'Linux', os.arch: 'amd64', os.version: '4.19.0-13-cloud-amd64', java.version: '1.8.0_282'
Driver info: org.xwiki.test.ui.XWikiWebDriver
Capabilities {acceptInsecureCerts: true, browserName: firefox, browserVersion: 86.0, javascriptEnabled: true, moz:accessibilityChecks: false, moz:buildID: 20210222142601, moz:geckodriverVersion: 0.29.0, moz:headless: false, moz:processID: 285, moz:profile: /tmp/rust_mozprofileSnXuFk, moz:shutdownTimeout: 60000, moz:useNonSpecCompliantPointerOrigin: false, moz:webdriverClick: true, pageLoadStrategy: normal, platform: LINUX, platformName: LINUX, platformVersion: 4.19.0-13-cloud-amd64, rotatable: false, setWindowRect: true, strictFileInteractability: false, timeouts: {implicit: 0, pageLoad: 300000, script: 30000}, unhandledPromptBehavior: ignore, webdriver.remote.sessionid: 941d7a8a-0fa8-4ebc-8922-8f7...}
Session ID: 941d7a8a-0fa8-4ebc-8922-8f7541824a30
	at org.openqa.selenium.support.ui.WebDriverWait.timeoutException(WebDriverWait.java:95)
	at org.openqa.selenium.support.ui.FluentWait.until(FluentWait.java:272)
	at org.xwiki.test.ui.XWikiWebDriver.waitUntilCondition(XWikiWebDriver.java:227)
	at org.xwiki.test.ui.XWikiWebDriver.waitUntilCondition(XWikiWebDriver.java:215)
	at org.xwiki.livedata.test.po.TableLayoutElement.waitUntilReady(TableLayoutElement.java:335)
	at org.xwiki.livedata.test.po.TableLayoutElement.waitUntilReady(TableLayoutElement.java:321)
	at org.xwiki.livedata.test.po.LiveDataElement.getTableLayout(LiveDataElement.java:64)
	at org.xwiki.mail.test.ui.MailIT.verifyMail(MailIT.java:239)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:688)
	at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
	at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
	at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
	at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
	at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
	at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$6(TestMethodTestDescriptor.java:210)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:206)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:131)
	at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:65)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:84)
	at java.util.ArrayList.forEach(ArrayList.java:1259)
	at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:143)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:129)
	at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:127)
	at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
	at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:126)