Why does Keynote collaboration keep renaming files and unsharing

Trying to work with 2 others on a Keynote.

They are using browser. I am also using a Browser from my Windows machine (where I do some photo editing and video work). I am using Keynote on a Mac as the main driver. At least 5 times now, whilst they have been working on it - they have been kicked out, and my local copy as been renamed with a 2 on the end, the last good copy having the original name in my iCloud Drive. Even if I rename back to original filename, I have to re-share with my colleagues each time.... THIS IS AWFUL and has resulted in lost work several times.

I convinced them to do this in Keynote over PowerPoint and live collaboration on O365, but frankly, this experience has been utterly garbage and they're quite rightly laughing at me. We're going to have to move back to PowerPoint for our next presentation unless I can resolve this, but this is infuriating as the result in PowerPoint is far less professional looking.

Can anyone please explain why this keeps happening?

Thanks,