Was not able to reproduce on Windows.
I checked the Linux log (Project, UE4) and did not notice anything meaningful there. I used GDB to get a backtrace from the core dump file. Attaching that and an image of the callstack of my terminal when the crash was happening.
Repro:
Result:
Crash
Epxected:
Viewport controls submenu opens
Frequency:
100%
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-41634 in the post.