A teleporter of the scale of “0.01, 0.01, 0.01” is invisible for new players that join. Moving or scaling it after a player joined makes it visible again. (Unpractical fix)
Add a teleporter to your Condo and set the scale to “0.01, 0.01, 0.01”. (Optional?: Reload your condo.) Finally let a player join after the teleporter already existed and they won’t be able to see it.
Other players should always see the tiny teleporter no matter when the teleporter was last moved or scaled.
Other players were not able to see the teleporter.
This bug existed for at least a year.