Dear Focusaurus,
Thank you for your post and I'm sorry you have been having this problem with the cello.
The cello works in the same way as the clarinet in the amount of air needed to sound the instrument. The strip controller does require some practice to get a smooth bowing action but you should get some sound just by running your finger along the strip.
It could be possible, as 0beron suggested, that you are playing out of the cellos range of notes, however the cello should load in the correct range when it is first selected. Just to make sure in split 1 try selecting the cello and using the octave up/down keys (the very bottom 2 playing keys) and see if you get any sound.
Do let me know how you get on, if the problem does persists please can you log a bug report? This will initially help our software team track down the problem, if they require any more information I will be in touch.
If you have any questions please do get in contact with me on +44 (0)1392 823000 or email support@eigenlabs.com
Regards
Aaron
Customer Services