@HazelBlakely
Since 3.5.x there are issues with backups and Pro recognising them after a crash. Not sure if your issue is that they are not created or if Pro does not tell you they are there when you open a project after a crash.
If I get a crash (which is more common for me in 3.5 & 3.6 than previous versions) I immediately go to the .backups folder and copy the file to another location.
You have to set Explorer to show hidden files. A '.' folder won't show in vanilla explorer.
Note that in 3.6 the backup .aprx is now a .aprx.tmp
When I open the original project file, Pro often does not tell me there is a backup, as well as deleting the backup if it exists. This took me a while to realise; I thought I was doing something wrong.
The backup copied to another location can be opened, checked, then saved to the correct location.
3.6 backups must be renamed by deleting the .tmp before opening.
I've not once had Pro unable to open the copied backup. Funny that.
Obviously, due to the *broken path handling of Pro you may run into issues depending on where you copy the backup to - I place it in the original project aprx location with a _BU suffix.
This behaviour has been seen on multiple computers after installing/upgrading to 3.5/3.6. A case was lodged with the locals but their conclusion was to request an update to the Pro documentation to better explain how to configure it and what the failure modes are. Yaay.
*Yes - the path handling is broken. Esri can try justifying the merits of their design choice but anything so fragile and susceptible to issues is broken in my opinion.
