Like many here, I am having various "issues" with enabling the passengers in PMDG aircraft.
Initially I started with the 737-700. I "enabled" seated passengers by checking the boxes in the GSX Updater/Installer. My first attempt was successful and I was pretty excited! It lends a whole new dimension to the sim and to the aircraft.
At this point I went to the 737-800 and upon entering the sim, I was sitting in a cockpit that was obviously the reduced graphics for the cockpit if you were viewing the external view of the plane (the pilots were actually being rendered as well. When I actually switched to the external view there was nothing but the cockpit structure floating in space without the rest of the plane
Perplexed by this point I exited and reentered the sim. This time the plane was completely gone from all views. Not even the cockpit was visible as previous.
At this point I exited the sim again and went back to the GSX Updater/Installer and unchecked all the boxes for the seated passengers. I noted that whenever you check and uncheck the boxes it automatically runs thru a process of writing files (You can see their names tick by very fast and are files with extensions like .JSON
Entering the sim and everything was fine. All the planes were back and each plane seemed perfectly functional as they were before I checked the seated passenger boxes.
I exited the sim and checked the boxes once again and reentered the sim and once again, blurry cockpit, floating clockpit, disappearing plane.
At this point I started reading all I could of the messages and notes. It was here that I found out two critical pieces of info. 1. If you change a livery, you must go back to the Installer and check and recheck the seated passenger option, and 2. The feature of seated passengers doesn't seem to currently work with anything but the default "official from PMDG" liveries.
This time I loaded the PMDG livery for each of the aircraft 737-700/800 and the 777-300ER and low and behold! It all works perfectly!
Bottom line (in my experience so far) You HAVE to use a PMDG Official Livery, no 3rd party liveries, and if you change the livery, you have to go back out and check and recheck the seated passengers boxes in the GSX updater program.
I know that several people appear to have irrepairable corruption to their PMDG installations and have to completely reinstall the aircraft. This hasn't been my experience and I feel for those that have to go thru that process to get their planes back
For me, again it's just a matter of using an official livery and unchecking and checking the boxes again.
I hope this info helps people. I know that these details are all included in the instructions somewhere, but you know how computer users work. Install it in a way that seems correct and it should just work
Hopefully they can patch it so that it works with all liveries.