I feel for you guys. As a UAD user, I've had a few issues myself but I don't use my UAD stuff in Pro Channel so I never have to deal with this. I can tell you a few things I sort of found out over the past few months. I don't know how true any of this stuff may be right now, but within the past few months, this is what I was told.
UAD and Sonar: When I contacted Sonar support about my UAD issues, I was told that UAD uses this thing called a "chaining API" that allows it to talk to the next plug in the chain. This can sometimes wreak some havoc and one of our bakers was working on a remedy for this. I do not know if it was finished by the time X3D came out, but I reported the problem (some of my UAD issues were on my end which I fixed by X3D) and I was told it's on UAD's end because their plugs do not work like other plugs...but there was a way to fix it by bypassing the chain API so the plug would behave like all the other plugs we use. When or if this will be/has been addressed, I have no idea...but I reported UAD issues and that's what I was told by a pretty powerful Baker.
UAD's report on it's issues and Sonar: "We don't test on Sonar in house anymore, so we can't really tell you if or when a fix may happen. We are aware of the problems people have with UAD in X2 and X3 though."
Danny to UAD Rep: "I'll beta test for you guys for free as I have all the plugs from you that I need. You went from having a special Sonar switch in your UAD control panel to not testing at all in house? C'mon, I'm sure the Cakewalk staff will accommodate if you can please try to work this out with them. If I can do anything to help, please let me know as we have quite a few UAD users in our Sonar community and I don't mind doing whatever I can."
UAD Rep: "Thanks, I'll definitely see what can be done about this and will keep you posted. If we need any additional beta testers, I'll let you know."
So that's all I can add to this discussion. I tried guys....I would have dedicated whatever I could to get these UAD issues resolved. Heck I can't even beg to be a beta tester for free these days! LOL!! Incidentally, I will try the Pro Channel thing with UAD to see if it happens on my end. I just use them in my track FX bins without any issues right now. I've noticed some latency issues as well as mono tracks NEEDING to be stereo interleaved or I get this demon, slowed down thing on a track. Stereo interleave fixes it, but it only seems to happen on UAD plugs where you have a mono track and use a stereo UAD plug. I'll report back with my findings when I try the stuff you guys have been talking about. I've been following the UAD issue threads, I just haven't had time to try some of the stuff you guys have been talking about. I'll be in touch.
-Danny