hello,
yes , I have this issue also, pitches back alot, its intermittent, seems to be a bit dependant as to where the stick/craft is when angle mode is activated. I have tried accel calib , trims, channels centered, none of which helped for more than a minute maybe, as it is intermittent.
Have built over ten naze32 builds none of which had this problem, Also tried another clone naze32 just yesterday as i though it was a faulty board, same fault still there. It is bad enough to make you crash sometimes (sometimes it will lock on and think “level” is around 45 degrees leaning back)