As you said, my Scene A is for playback of tracks (inputs + regular)
My Scene B is used to playback the recording.

Track 1-5: samples playback, Flex Machines
Track 6: stereo input A, Thru Machines
Track 7: stereo input B, Thru Machines
Track 8: flex recorder (recording all internal and inputs tracks)

I works! and it’s fun!

Each Scene, from 2 to 15 are for FX (reverb, delay, filters…)
Scene 16 is to playback the recording and thus, I’m able to change the pattern using the great Transition Trick, and moving slowly from Scene B to Scene (with the recording of the previous pattern) to Scene A with the new pattern.

The trick works fine.

The problem is that sometimes, for reasons I am not able to define, the 8th track stops the playback of the recording stuff “+ >” and just plays a blank part “+” and then I’m forced to bring back the slider quickly on the Scene A

Tried my best to dissect the problem (trig? recording trig? length of the recording trig? position of the slider?) but in vain…