Assertion failed error on quit game

I received this crash when quitting game (via connecting escape input event to quit game node)

Assertion failed: IsValid() [File:Runtime\Core\Public\Templates/SharedPointer.h] [Line: 849]

It occurs only on packaged builds (Development and shipping)
It is a blueprint only VR project in 4.20.

Any advice to investigate the cause would be amazing! - Thanks in advance guys.