When pausing a widget animation by using an event using the event track to pause the animation the editor crashes when you play the animation via PIE or standalone.
4.15.3 - CL 3450819
4.16.1 - CL 3466753
4.17 - CL 3505911
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-46558 in the post.