Content Aware Fill crashes AE when MGJSON asset is used.

I've been dealing with seemingly random hanging for months. Narrowed it down to a combination of using Content Aware Fill ("CAF") any time there is a MGJSON file used anywhere upstream from where content aware fill is used. 

• After Effects hangs on the next save after the CAF completes.
• I can save if CAF has started but not yet generated frames.   
• Autosave after the CAF completes also causes the hang.
• MGJSON can be imported in the project, the hang only happens when it is used in a comp.