Crash clicking the question mark to show Viewport controls

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:

1. Open any project.
2. Click the '?' in the lower left corner of the Viewport

Result:
Crash

Epxected:
Viewport controls submenu opens

Frequency:
100%