Hi ajb2k3 & teastain,
thanks a lot for your advices.
I will look at micropython side but I'm very concerned by the fact that the UIFlow blocks I used have been deprecated without notice. I'm on a very bug hurry now.
I went back to V1.9.8 firmware on my M5StickCPlus and M5Core and everything is working again now. At least temporarily.
Have a good week
S