Not a regression as I was able to repro this in 4.25.4
The bug doesn't occur every single time, you may need to try disabling/re-enabling the setting and/or clicking on the menu dropdowns a few times. It happens more often that not though.
Result: Dropdown menu flickers and is unclickable
Expected: Dropdown menu looks and functions normally
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-105239 in the post.
|Component||UE - Editor - UI Systems - Slate|
|Affects Versions||4.25.4, 4.26, 4.26.1|
|Created||Jan 7, 2021|
|Resolved||Jun 2, 2021|
|Updated||Dec 2, 2021|