quick question about ignores

I would suggest testing your patterns with an unshared local folder. Basically, just create a new folder without sharing it with any other device, add your patterns to it, and then copy each of the file types into it one by one. You will be able to see in the Web GUI whether the local state has changed or not (i.e. the ignored files should be removed from the local state).

You haven’t mentioned what operating systems and/or filesystems are in use, but note that if your NAS is Unix/Linux-based (pretty common) and some of other devices are Windows, Android… using vFAT / exFAT… etc. the following two ignore patterns are not equivalent:

!*.z64
!*.Z64

If you want to catch both lowercase, uppercase and mixed-case file/folder names, you’ll need to tell Syncthing to ignore case:

(?i)!*.z64