The profile plot from post #52 is interesting as it does not show a "vertical" drop, probably more likely between 30-40 deg trajectory. I also agree with a post that highlighted the two ADSB blips where there is an extended gap between responses of say 15 seconds, where both steep descents seem to originate, was there some sort of electrical fault or factor? From both ADSB cutouts the aircraft initiates a steep descent and lurches left, from what the plot shows. After the first there seems to be a turn of sorts back to the right and some recovery action by 10,000 feet then a second gap in returns and it goes back into the final steeper profile.