This past weekend I was 4 minutes into my second of four flights for the day when two unexpected things happened:
1) The video recording simultaneously STOPPED to both the on-board micro-SD card and to the video cache on my iPad Pro. Unfortunately, I didn't recognize this had occured until after I landed.
2) The gimbal went completely bonkers for about 60 seconds - first, it pointed down and left and then it wandered around aimlessly tilting left, then right, then left, then right again in slow motion - sort of like it had too much to drink!  Before this incident, the gimbal horizon on my P4Pro had been perfectly level for dozens of flights. This was not the known gimbal overload issue where the gimbal suddenly tilts almost 90 degress to the side during a fast turn or when flying sideways into the wind (which is a major PITA, but I've learned to live with this issue). No - this was something NEW and completely weird. I tried a 360 degree yaw to see if it would correct things - nope, the gimbal was still acting like it had just had its electronic bell rung.
3) After another minute or two - the gimbal finally returned to its normal, perfectly-level horizon performance while flying. Unfortunately, I had not noticed that I was no longer recording video, so the entire flight session was a loss, including the cached video on my iPad.

After I landed the P4Pro and removed the battery, I discovered what I am convinced was the CAUSE of the weird behavior - I had a BUG in the electronics - literally a BUG!  I had carried the P4Pro back to my car for a closer inspection. As I pulled the battery out, the P4Pro was tilted slightly downward and I saw something tiny fall out of the battery compartment onto the concrete parking lot at my feet. When I bent down to inspect what it was, I found a tiny, curled up, burnt up ANT!  I then remembered that when I was swapping out batteries before this flight with the P4Pro sitting on my acrylic landing pad in the park, I had noticed, as I often do, several small ants crawling around on the white legs and body of my P4Pro. This is not unusual when launching your aircraft from the grass. I had never been concerned about these tiny six-legged hitch hikers - before this event. I had always imagined the ants getting a spectacular ride!

LESSON LEARNED:  When swapping out batteries with your P4Pro sitting on the ground - DO NOT LEAVE THE BATTERY COMPARTMENT OPEN for any period of time. Instead, immediately put a fresh battery in after removing the expended battery. Otherwise, a tiny insect, specifically an ant, might crawl inside your P4Pro battery compartment (while you walk several yards to get a fresh battery) and later wreak havoc.  I got very lucky -- the ant could have randomly electrocuted himself on critical flight control circuitry instead of (I'm guessing) on the gimbal control circuitry.  No permanent damage was done this time (except to the poor ant!).  Two more flights the same day were uneventful with perfect gimbal level and rock-steady P4Pro flight performance. The ant that fell out of my battery compartment might not have even been the little fella that caused the problem. I wonder if I have other tiny dead ants still inside the P4Pro body?

I'm now considering floating a light mist of OFF bug spray over my turned-off aircraft just prior to my next flight session to keep ants and other tiny insects off the legs and body of my aircraft and sensitive electronics. But I'm afraid the spray might contaminate sensitive electronics.  So, maybe one of those bug spray wipes would work. Any thoughts?

I now wonder if a few - maybe just a few - of the "my P4Pro suddenly fell out of the sky stories" on this forum might have a completely "nature-all" explanation. If you catch my meaning!  

LOL  Now that's a new one. Might need a good mist of "RAID"

Oh wow, that a funny story glad something didnt happen during mid flight and caused your drone fall out of the sky

Ha ha, a good lesson! Thanks for sharing with us! Wish you have great time.