Okay so I just tried another workaround. It’s semi satisfactory.
Not got midi set up right now so just using audio but in theory should be same.
Set the scale mode to ‘per track’
Set the bassline track scale to 64/64 but master to 0016
All other tracks to 16/16
Consider the first page of your bass track to be the ‘active’ loop, the next 3 pages each have your variations.
Copy and paste from your 3 variations (pages 2-4) into page 1 as required. The bassline pattern changes while the rest ofthe tracks stay as they were