Pianoteq 4 with Ableton Push controller

I find the default behaviour of Pianoteq 4 with the Ableton Push problematic.
When you press a key you get the normal velocity sensitive note, however Pianoteq is responding to channel aftertouch generated by the Push in a really weird manner:
The note is held as expected but an additional voice starting on the same note is heard but pitchbends up according to the aftertouch value. The result is not desired or musically useful to me (or anyone?)
I'm observing the midi into Pianoteq through it's midi monitor window in the options page of the Pianoteq VST plugin. The problematic messages are Aftertouch coming from the Push.
I've tried reassigning Aftertouch on this page and it does reassign to another parameter except that I don't want aftertouch to control anything. If I delete the Aftertouch entry in the table it goes back to the horrible pitchbend behaviour I describe above. 
Please help!
Thanks