I have Sonar X3e Producer Edition installed, and the behavior here works the same as in earlier versions of Sonar, in that this issue is still an issue with the VSTi version of the synth.
I don't happen to have the DXI version installed, so I cannot try things out there.
I just wanted to let you know that I was unable to use the midi bank and patch select buttons on the midi track, to get it to actually properly switch the bank. I even tried the midi channel 1 tip in one of the earlier posts.
I DID, however, have no problem with changing bank and preset in the UI for Z3ta+, after opening it in the synth rack. That worked just fine.
So, if you are just loading a single sound into a given instance of Z3ta+ you can get it properly loaded by just changing bank and preset that way.
I hope that helps,
Bob Bone