Currently experiencing something quite similar to this issue. Experience with no team create too.
I used to have your exact issue, starting from about a week ago until about an hour ago, after which point from which all save attempts have failed. Trying to use “save as” or “publish as” gives me this error message.
The only workaround to this that I have found is to just save it as a file, close Studio, open the file and save it to the original experience. Which is quite a bit annoying, and I sincerely hope Roblox fixes this soon.
I believe the timing of your upload specifically matched an outage we were experiencing on Monday. So sorry for that. If you try it again, does it work now?
My thinking is that you ( @016er ) have a separate issue [now resolved] vs the main issue where there is a success followed by a failure followed by a success.
We believe we have found the underlying issue, and are working on a fix for a future release of Studio. Thanks for your patience, and sorry about the inconvenience of having to publish a second time as a workaround in this case.
What about the Internal Server Error (HTTP 500) publishing error after adding model(s) in studio? I made a forum about this. However, it isn’t under a Bug Report since I’m not a Regular level yet, so I’m not sure if it will be read by a staff member. It seems to be a crucial bug, so I just wanted to reach my hand out further than I already have.