Logic Pro X Drummer creating empty regions

Hello,

Has anyone encountered this problem? I can create a new song and start with a Logic Drummer track and everything works fine... Default "Kyle" shows up with his SoCal kit and a couple of regions populated with drum beat data appear in the Tracks window.

...But if I try to add a a Logic Drummer track to a pre-existing song (also created using the same version of Logic; Logic Pro X 10.0.7) everything happens as it should except that the two regions created in the tracks window are empty and I hear no drum sounds from them when I press play. Using a midi controller keyboard, I can trigger the drums sounds manually, so there's nothing wrong with the kit or the samples... but the controls in the Drummer plugin editor window have no effect. Moving the yellow dot across the Loud/Soft, Simple/Complex field does nothing. Sliding the 'Kick & Snare' and 'Hi-Hat' sliders right or left does nothing. I can change the Drummer character but the regions stay empty and I can change the drumkit but still, the regions stay empty.

It seems I can only create a Drummer track in a new song... I can't create one in an existing song...? Can anyone please help me out or offer troubleshooting steps to try? (I've already trashed the Logic Preferences)

Thanks,

Yahenda

When you create a new empty project with one audio track, save and close it,

reopen and create a Drummer track, this happens ?