My contacts 'assigned photo' will not stay saved ?!?

Give this a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.

NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.

Good day to you smartblondegirl, 

A couple things that would be helpful to know and allow us to further isolate - 

1. Does the issue persist regardless of which device you change the image on? If you’re not sure, let’s test that. We’re linking a couple articles with the how-tos below - 

Add or change contact pictures in Contacts on Mac

Edit contacts on iPad 

2. When you change the image, does that sync to iCloud? This you’ll check by logging on to the iCloud website and looking at the Contacts app there - iCloud

3. Does this happen with all contacts or specific contacts? 

Thanks.