I have been LR 5.71 (I see there's supposed to be a 5.7.1 version but my Mac says my software is up to date).
I have my program set to back up when I exit LR. I don't use it every day, not even every week. This problem just began and I can't tell if this is a big problem (work not being saved but that appears not to be the case) or just another LR glitch.
I also have found that when I work with the HSL/Color adjustments LR closes immediately.
I have reported both problems repeatedly but they continue.
Please state the operating system version NUMBER (and do not use words like "latest" or "up-to-date")