Steps to reproduce the issue

1. Install "clear" Joomla 4.0 Beta 1
2. Open admin panel on mobile device
3. "Add new article"
4. Scroll down where article category dropdown shows "Uncategorized"
5. Click on it (not on arrow)

Expected result

Categories dropdown shows

Actual result

Page suddenly reloads

System information (as much as possible)

Server:
Windows 10 x64
Nginx 1.17+Apache 2.4
PHP 7.3 x64
Joomla 4.0 Beta 1

Mobile browser:
Android 9
Chrome

Additional comments

If it isn't bug, it's strange

P.s. - pls, change my issue title if necessary. Sorry for my English