Tag suggest feature is broken

Steps to reproduce:
1. From any page in XWiki, click on [+] and introduce a tag name to create a new tag.
2. From another page, click on [+] and type first letter from the previously created tag and select the tag from the suggested list.

Expected result: the existing tag is added.
Actual result: when selecting an item from the suggested list, a redirect to null page is happening. The links of the suggested values consider the page name = 'null'.