Clicking on the Set Key Time option when right-clicking a key in a UMG animation will crash the engine. I have reproduced this in a blank project.
-
Create a new blank project
-
Create a widget BP
-
In the Widget, create a new animation
-
Add any component to your widget so you can have a key on the timeline
-
Add a key for your component in your animation (like position or whatever, anything works)
-
Right-click the key and select Set Key Time
This happens 100% of the time.