Just a question and forgive my being obvious.. The Customs zone, was it successfully downloaded to your drone before flying into the zone?
Incidentally I had a weird experience with my
Air 3 in the last month.. 26 GPSs locked, area I use often.. Phantom restricted zone warning.. Backed off and it would not let me out via original path.. Tried all routes.. Warnings etc. Couldn't fly home.. Battery died & lost contact..
Recovered next day intact.. But sent back to DJI for warranty analysis.. They sent me back a new drone the next day so there must have been a fault.. Worth a try for peace of mind.. Not your use case I know