With a hotfix to the game that was applied a little while ago, we’ve removed a setting that was restricting players’ ability to consistently see and interact with others in their group in the four Shadowlands zones and the introductory Maw.
Now, as before in Battle for Azeroth, joining a group should bring you to the party leader’s perspective. Players who are in and out of War Mode will remain separate, as always.
An exception that remains is the max-level version of the Maw. Players in the max-level Maw may not immediately be able to see one another when joining a party. However, leaving the max-level Maw (to Oribos) and returning should bring members of a party together.