You should try to be more accurate in your reports, because it's very difficult to understand the issue, without *any* detail about the scenery used and the kind of parking used.
Assuming you used a gate with a Jetway, as explained so many times in the forum, in order to see Passengers/Crew boarding, the Jetway must be both *detected* by GSX AND it must have Docked too.
There are many reasons why the Jetway couldn't be detected, most common one is the scenery is a Marketplace scenery, so it can't be read by GSX, or GSX might have loaded the wrong airport file, because the correct one might have been rejected for some reason ( corrupted file, too big file, etc. ), and all of these issues will be fixed with the upcoming Navdata API upgrade, which will remove the need for GSX to read the airport file directly.
And, even if the jetway could be Detected, in order to see Passengers, it must have Docked correctly.
If any of these conditions are not satisfied, Boarding/Deboarding of Passengers and Crew will be only simulated, going fast with no people to see.