I use several GP instances on my system because of different audio interfaces and different application tasks. I manage the instances using AppleScript.
Now I have noticed that the scan result from the Plugin Manager delivers different results, for example Amplitube 5 is marked as ‘failed’ in some instances and accepted in others. When I run ‘Rescan Failed Plugins’ again, there is sometimes a positive change, but unfortunately this is not usually the case.
Plugins from other manufacturers are also affected by this phenomenon, and I cannot understand why GP Plugin Manager delivers different results. Hopefully there is a simple solution to this and the error lies with me (user error 
).
We’re looking at having a shared list for plugins across instances but it’s not there yet.
But to explain what’s typically happening:
Some plugins want to connect to their home servers, either to check for updates or to do license validation and this can occur during initial validation. If there is an issue with connectivity (no internet but plugin tries anyway, remote server is down or too slow), the scanner will eventually “give up” rather than allowing a single errant plugin/server from preventing other plugins from being validated. If that happens, then the plugin will be marked invalid.
Typically, deleting the plugin from the list (in the plugin manager window of the particular instance) and rescanning should fix it.
2 Likes
Thank you very much for the explanation 
. I will follow your suggestion 
I had this same issue (missing plugins or scanning for updates stopping progress). My performance laptop never goes online. I don’t want an update to slow down or derail my system. This caused issues with several plugins. I was able to go into settings in each plugin and uncheck “scan for updates” or “use offline”. That solved the problem for me. I also found Rescan failed plugins didn’t solve the issue.