There seems to be a Major bug with expertise levels. It seems depending on how items are becoming proficient (playing with item / donation of mats/weapons) different calculations towards expertise level take place, resulting in varying max expertise caps.
For example I got all items proficient. The lion share was performed by donating mats with some donated gear pieces and a little playtime sprinkled in.
The result is that all items are proficient but only a lvl of 20 was achieved, although 30 is supposed to be the maximum. It even shows some progress towards the next level (80/140) which ofc cannot be reached as everything is proficient already.
Here are some examples from other players:
Also refer to the following thread in the general discussion forum for other user experiences:
https://discussions.ubisoft.com/topic/155984/inconsistency-about-the-max-expertise-level-using-different-expertise-leveling-method/37?lang=en-US
Please take a look into that.
Thanks