generative fill does not finish in either this version or the most recent version

It seems to have fixed itself. Perhaps the Adobe servers were overwhelmed or another problem with the servers.

@si conehead can you share more info on what the issue is, screenshots or video of what you are seeing?

It may help if we could see your Photoshop beta System Info. Launch Photoshop beta, and select Help >System Info...and copy/paste the text in a reply.