...just happened...
Started the Stage and moved to the desired performance and Rig. Started playing and sounded...off , kind of thin and trebly..gain level on the low side to where it is supposed to be. Checked Vol an Tone on the guitar, volume pedal range and calibration and mixer channel settings...All normal. Switched the Monitors on and same thing (was on Headphones).
Switched on the Catalyst (connected to Monitor out) and also there the same.
I then moved to another Performance and all sounds normal, back to the original one and...now it sounds as it should!
Tried to reproduce it starting all over again, with and without RM (iOS) connected, running the exact same sequence and couldn't, all good and normal....
Absolutely no cue what it was....