Mutable crashes when trying to connect Group Object referencing an External Object

Hi again Chad.

I would like to give you good news, but sadly, I have not been able to reproduce your issue. Could you be able to submit us a reproduction case (the content of an example project) so I can reproduce and debug the issue locally? And just to confirm, you are running the 5.5.4 version of the engine, right?

Have a nice day.

Daniel Moreno