Groups assignment remove automatically

I am using UAM 1.2.2 and my user assignment to groups change unexpectedly. some users keep their groups and some been removed.

How can i found it source?

What happen if i upgrade to new version of UAM? does my assignment remove or not? what will happen for my invitation codes which is more than 2000 items.

https://www.ads-software.com/extend/plugins/user-access-manager/