ALT HOLD activation causing RAPID CLIMBING 10m ! ( pulse to throtle )

HEllo , i have little problem with AC 3.3 on Y6B. ( pixhawk )

When i activate althold copter get big pulse to throtle, climb 10m . Then all work ok .
This problem coming ONLY in activation . Whats wrong ? Someone got same problem ?

Can you post a log. Is it only happening when you switch to AltHold or to any mode? If it happens in all modes, it can be related to the buzzer interfering with the Accels.

You do have the throttle stick in the middle, right? If you have the throttle stick up above 60% and switch to alt hold, it’s going to climb until you center the throttle stick.