Not saving, just creating a .tmp file and all the work is gone

This is an issue that's been happening the last month or so. I make dozens of files a week, most no problem so I do go back and check that the ai file has been saved, usually I just check the pdf or other export. Well surprise surprise, every so ofter when you hit save in illustrator it doesnt do that, just creates a .tmp file and all the work is gone. This has happened on both my desktop and mobile setup on laptop. Both computers are updated with the latest illustrator version. I see on the bug reports this is happening to a lot of people.