DAMN IT, It’s something COMPLETELY unrelated and nothing to do with Steinberg!
I tried creating a template from scratch. Loading a 3rd party plugin, no problem.
Then, I loaded my FX chains that contained UAD plugins. The MOMENT I did, I couldn’t load other 3rd-party plugins anymore. So I was really perplexed.
So I checked my UAD-2 PCIe card software, and I was behind quite a couple of updates for this card.
I downloaded the latest UAD software for my card, restarted the computer, and BOOM. Now, I can load OTHER 3rd party plugins alongside my UAD plugins! The UAD plugins are on a group channel in which other audio tracks with other 3rd party plugins were on were connected to it, so I think there’s some kind of disruption glitch due to the un-updated UAD software driving the UAD plugins.
Quite a shitshow, but I guess I’ve figured out what the problem was - my UAD-2 driver software! Once I’ve updated that, every other 3rd party plugin now loads, no problem. SHIT!
Anyways, sorry to disturb everyone! Hope that those with exactly my same setup and problem could refer to this! In this case, absolutely not Steinberg’s fault.
Now a happy camper!