Hi again ,
So if i'm following you properly, you're still able to use Analog Lab 2 but not Analog Lab 3 through Logic.
If so, i'm pretty sure that the issue is more coming from the Auvaltool (Au validation tool) which may for any reason not work properly.
Normally a complete uninstall/reinstall should already have solve your problem and it doesn't seems to be the case.
I would eventually suggest you to ask the Apple support to see if they have any suggestion to offer you as i do not really know what may cause such issues.
They will perhaps be able to provide you another Auvaltool version or try at least to repair it if possible but in any case i think that it would be worth a try to ask them if they have any suggestion to provide you.
In any case, i stay at your disposal if needed.
Logic Pro X, macOS High Sierra (10.13.3), null