That is interesting, I had that sort of “quirk” last flight in a PG area (on the ground, airport in PG area) and one single time in this area shortly after takeoff. The rest of flight was uneventful in this regard.
But it was not only a dialog box for me, for me I was put for some seconds in the steam VR idle “world” and a MSFS title picutre with a waiting animation came up.
The sim itself on the other hand didn’t pause during this event. A sim hang would look different. It looked more like that the sim had lost communication to steam VR for a few seconds.