You mentioned the program change channel... this is not relevant to your issue, as pitch bend is not a program change.
What is it exactly that causes the pitch bend? Is it the sus switch? I am guessing it's that, because it's probably NOT a trigger... note messages should not mess with CC values like pitch. You'll want to find out exactly WHAT causes the issue and change its settings. As far as different midi channels in BFD, I am guessing in the preferences you have midi receive to Omni. I advise changing that to the channel of your Zendrum so you can isolate channels for different applications.
Hope that helps,