Excuse my ignorance… I mainly use M$ Flight Sim 2020 to sight see, lol… while flying today I noticed a friend (Panther, most of you probably know her) on my main map. So I clicked on her to join. It first asked if I wanted to join the West US server, so I did. I kept seeing her on map but not flying. Didn’t even know you can do that in this game/sim.
Anyway… can you actually see and fly next to each other… was never able to spot her. Just wonder, thanks.
Yes, you can see and fly with other friends. Like you mentioned, sometimes it depends on whether they are on the same server, and sometimes it depends on how busy the airspace is…although it is supposed to be biased to drop strangers in favor of friends. It also helps to have the GAMER ID tags on to help locate one another…but yes, you should be able to fly together.
I never see anyone of y’all. Regardless of when I look, everyone is offline.
So unless you all blocked me something is weird there…
Really happy to hear that Panther is still around somewhere. 
Wheels
I think you have to be Xbox friends.
Yeah I know, I have added over a dozen Mudspike members, and on the day I added them I could see them. (And then never again).