I wish I had known this thread existed before starting my own on the same topic. The search turned up empty back then.
For reference: Seeing generic models instead of actual plane models/livery lotto - in flight only
At one point I thought I had found a solution to the problem only to be greeted by generic aircraft instead of actual models a couple of days later.
Please Asobo, fix that problem in one of the future SU’s. After spending a considerable amount of money I can’t see the planes I bought in multiplayer. For me that kills the immersion into an otherwise beautiful product and judging by the vote count I am not alone.