That's interesting. I've done 2 flights with the Fenix (don't think it's Fenix related) and I have found when requesting boarding the passenger's load within 5 seconds.
Surely is not related to the Fenix. As explained so many times on the forum, if a gate has a Jetway, the one and only reason why passengers boarding is only simulated ( no passengers, happening very fast ), it's because the Jetway hasn't docked.
If you see the jetway docked, the likely reason is the jetway hasn't been DETECTED by GSX. This is more common when using the SU10 Navdata, because when using it, while we have several advantages, like Marketplace airports compatibility, faster startup times and more reliability in general, we are also MISSING important data we have when the Navdata is Disabled and the .BGL is read. That's why we don't enable the SU10 Navdata by default yet, because it's still incomplete.
The following post explains in more detail all the issues that might cause jetways to not be detected correctly, when using the SU10 Navdata, and how this should be eventually fixed for SU12, which will give us even more data than we ever had from the .BGL:
https://www.fsdreamteam.com/forum/index.php/topic,28663.msg187336.html#msg187336