What changed? Version of your OS and CC down to the last decimal point? Any new software or virus definitions installed?
AE CC Version 220.127.116.11
No new software installed
Particular, Element, and Optical Flairs plugins are installed on my machine but not my coworkers so that shouldn't be the issue.
Pro-tip, I wouldn't save over the original file anyway. Save it as an incremental version number of your file.
I may save often as a force of habit, but I also use the increment and save feature about once an hour.
Speaking of, does it give you the increment and save option?
When you say it "doesn't work", do you mean it does nothing at all when clicked or do you mean you can't click it or do you mean that you can click it and it acts like it's doing something but it isn't actually saving the file?
Increment and save works fine but we don't use it because we are using Alienbrain for version control. When I press save literally nothing happens.