If you are working with premade midi tracks as the primary source for triggering your bass vst, there is a way to have everything play in correct keys without manually editing the source.
 
Look for documentation on "drum map manager' and 'assigning a midi track to a drum map".
Eventhough "drum" is mentioned it will work with a bass vst. 
It basically will detect the the source midi notes and pass corrected notes on to the vst in real time.
 
Very useful stuff.

Even though your issue is solved , I noticed you mentioned that this doesn't happen with drums.
Do a little experiment with Studio Drummer using the piano keys in the piano roll mentioned by Abacab. Make a note ofthe keys that trigger the different drum types. Then do the same with Addictive Drums 2.
You will find out that some of the drums being triggered are different for both programs.
That is why getting a handle on drum maps is so useful.
Sorry to harp like a seal but I'm OCD.
 

StuH
Even though your issue is solved , I noticed you mentioned that this doesn't happen with drums.
Do a little experiment with Studio Drummer using the piano keys in the piano roll mentioned by Abacab. Make a note ofthe keys that trigger the different drum types. Then do the same with Addictive Drums 2.
You will find out that some of the drums being triggered are different for both programs.
That is why getting a handle on drum maps is so useful.
Sorry to harp like a seal but I'm OCD.
 

Thanks for the info, I'll do that. Midi has always been a thorn in my side for some reason, but I'm starting to learn more about it. 
 
 

If the Ample Bass you are using is the lite (free) version of one of the Ample Sound bass vsti's, then it definitely has a limited range. I was on their website recently and noticed that about the lite version. It is, of course, also a much smaller program sample-wise than the full version but the lite versions do sound really good on their demos. I have their AGG vsti, very impressed with their stuff.