Matterport VR not opening FF58

Matterport used to open and work well, I just had to allow access, but suddenly it no longer opens showing a black screen. Still works in Chrome, but not in Pale Moon. I don't remember modifying anything, did a system restore and started in safe mode - same thing. The only thing that may have changed was Chrome downloaded something - a new version? - without my knowledge. However, the system restore did not reverse whatever they may have done. I'd hate to sssswitch to Chrome every time I need to open a VR link...

Any thoughts? Thank you