old users can see broken presence indicators on new users

[dwrensha]

To reproduce in the Sandstorm app:

1. Alice makes a new Wekan grain.
2. Alice invites Bob through the in-app (+) button.
3. Bob visits the grain.
4. Bob sees green presence indicators for Alice and Bob, but Alice sees Bob as not connected.

I have been unable to reproduce this outside of Sandstorm, but I don't see any fundamental reason why the problem would be confined to the Sandstorm app.

[dwrensha]

I managed to reproduce this outside of Sandstorm.

1. Alice invites Bob to a board and Bob accepts the invitation.
2. Bob navigates away from the board.
3. Alice changes the title of the board.
4. Bob navigates back to the board.
5. Alice does not see a green indicator for Bob!