Bug or feature in 4.0.4dev?

I’m observing a strange behavior in a 4.0.4dev’s parameter:
PSC_ACCZ_IMAX changes its value by itself !
Right now it shows 332.9578 in “Full Parameter Tree” (Mission Planner Beta), a value that i didn’t enter for sure.
Another time it was over 500.

Is that a bug or maybe a feature ? (maybe like MOT_THST_HOVER, which learns its value)