Since SU5, multiplayer group flights have been difficult as other players will appear and disappear at random intervals.
Last night, a group of about 8 of us were able to compare notes as we flew together in Florida. We noted that aircraft in front were more likely to disappear. When a player vanished, they usually vanished at the same time for more than one other player - suggesting it’s a server rather than local/install issue.
And it is a fairly big problem, because it kind of ruins the multiplayer experience.
Note that this is not a distance related issue - we’re all well familiar with nametags vanishing at very close range, and other aircraft turning invisible just before you’d hit them. This is something else introduced by the latest sim update.