Prototype pfevidw/thumbnail images

How do I change the ‘Prototype’ thumbnail view that is shown?

I know how to change ‘Project’ thumbnails… It’s ‘Prototype’ thumbnails I want to control.

There’s no options shown for ‘Prototypes’

Please advise as my prototypes are showing odd frames as the Prototype preview?

*preview/thumbnail

Did you find a solution to this? Thanks!