Captivate Video Crashing when Published

Hi forum, 

When I Publish > Publish to computer > Publish as video, unfortunately, my Captivate crashes and won't publish as it used to. I'd like the .mp4 export as I'll be joining it with a Premiere project. Any ideas as to why Captivate is crashing? I have the most updated version of Captivate (11.5.4), a mac, Catalina, and I've done this many times before. 

Thank you for any useful help you can provide, 

Cassy