Screenflow 6.2.2 Runtime Error While Editing

Hi

I've recently been getting this constant runtime error while editing projects, specifically while chopping and cutting audio or video clips.  This is the exact message I get.

ScreenFlow has encounted a runtime error that can affect its ability to continue operating.  Please save your work and relaunch the application.  If the issue persists, please contact technical support and quote the message:

*** -[__NSPlaceholderDictionary initWithObjects:forKeys:count:]: attempt to insert nil object from objects[0]

Any ideas as to why this might be happening?  When I quit Screenflow and open it again it seems to work fine for a bit and then I get the error again.

Thanks!