"...joining existing instances that may cause you to be unable to see other users"
This was brought up as an issue with the Upstream Provider today (07/23/2025) however this has been an issue for at minimum 3 and a half months. There is a fix that is tedious but allows people to be seen correctly.
-What the issue looks like:
  1. When joining a new instance, people will appear invisible to you but not vice versa.
  2. You find someone standing in place as if they are Desktop, but that player is not actually standing there and/or not on Desktop.
-Current immediate fixes:
  1. Going through each player using the "In Instance" tab and changing the Avatar Visibility (from hide/shield to show).
  2. Rejoining the world (not a guaranteed fix).