Hi Matthew,
Thank you for your answer. The funny part about this crash is that it appears after reopening the project and opening the BP with circular reference (or any level or asset using it, I guess). Before exiting the editor after creating this circular reference everything works fine and there’s no sign at all that we created something that will destroy our work after exiting UE4. It would be great to have some kind of warning after creating such reference or some way to repair BP with it. Other way it’s just a trap some may fall into without even realizing why. I attach files created by Crash Reporter here. Let me know if you need anything else. 
Speaking of references, could you please look into below issue as well? It bugs me for some time as well: Reference variable value disappears in child BP instances after changing the name of the variable in the parent - Programming & Scripting - Epic Developer Community Forums
Thank you!