Hey guys, after going crazy trying, installing, removing, uninstalling, and reinstalling the new 3.5.8 update, after which drivers, baggage handlers, passengers, etc. started appearing with the famous and annoying pink textures (also objects like trucks, tugboats, etc. disappeared), I finally found the solution I'm sharing with you.
There are two different problems: One is the passengers sitting inside the plane, and the other is the rest of the pink texture glitches that occur outside the plane, plus the disappearance of objects, etc., starting with the 3.5.8 update.
The solution to the latter is:
1: Uninstall and reinstall GSX from FSDT Universal Installer
2: Even if it shows that you already have the new 3.5.8 version, you must update from the button at the bottom UPDATE ALL or UPDATE 1 SELECTED (essential).
And the solution to the pink seated passengers is:
1: In the case of the FÉNIX, check that all the livery folders you've added to your Community folder begin with FNX_32X or fnx-aircraft-32X (essential). Once that's done, open FSDT Universal Installer, click on Config, and once it has loaded the aircraft you have, in the lower right corner under Seated Passengers in 202X, you must uncheck and recheck Fénix A32X in the case of the Fénix and close it.
2: In the case of other aircraft, it should be something similar, although I haven't had that problem yet, so I haven't tested it.
I hope I've helped you guys with this annoying problem. And I apologize for my English translation...