The placeholder text from Administration > Extensions does not disappear when start typing on Edge

STEPS TO REPRODUCE:

1. Login with Admin
2. Go to Administer Wiki > Extensions
3. Place the cursor on the beginning of the placeholder text on the search box
4. Type the name of an extension

EXPECTED RESULTS

When the user starts typing, the placeholder text 'search extension...' dissapears.

ACTUAL RESULTS

The placeholder text doesn't dissapear when start typing. However, if all typed characters are deleted and the user starts typing again, the text dissapears as it should.

The issue reproduces only on Edge browser.