A few problems on my end. I just sent UAD support an in depth description of my issues. Just in case anyone is curious, these are the problems I've seen with 6.4. Going back to 6.3 totally fixed me. I'll spare you the details, but here are my issues.
Sonar 32 bit excessive crashing with 1176 SE: Projects with UAD version 6.3 that were saved with an 1176 SE will crash when opened now. Pressing playback crashes Sonar. Dragging into another bin or re-ordering a chain crashes Sonar. Opening the project in safe mode allows the project to play once you remove the 1176. Bringing it into the project manually will crash Sonar when you press play or drag/move the plug.
Sonar 64 unrecognized CLSID for the 1176 SE: It claims it can't recognize the plug due to it being saved in Sonar 32. However, a menu pops up and it gives me an option to use the 32 or 64 bit plug. Both options work and both options load the 64 bit plug. Weird thing here, there are 5 other UAD plugs in that project that were saved from the old version. No CLSID warning for any of them or any issues opening in Sonar 32 or 64.
Default 64 plugin folder issue: we should have a choice were we install our plugs. I so hate that Stein VST folder. I cut them out of there and pasted in my Sonar 64 vst plug folder where they belong. I did try things in the default Stein folder first though. It doesn't matter where I put them.
Order of UAD plugs additional latency warning: Inserting a Sonar or Waves plug ( or any other plug) in between two UAD plugs in my bin gives me a message saying additional latency will now be added since there is a plug that isn't UAD in between two UAD plugs. At the end of it, it says "Latency -21". Whatever that means....probably 21 ms.
What I've done so far: I have uninstalled 6.4, deleted all files and folders, went into the registry and deleted everything UAD, re-installed and I'm still having this issue. So I'm back on 6.3 and there are no issues. I didn't have time to test all the plugs to see what others may have given me this problem as I don't have the time. There could be more...or hopefully, it's just this one plug and they will see it may have a bug or something. I'll report back here once I hear from UAD support. I hope you guys have had better luck than me.
-Danny