I was in the Miranda Docks, then teleported to Avery's Court, Skull Island using my "Skull Island" button. This successfully marked Miranda Docks as a return place. I then went to the bazaar, but needed to visit my house. I went to my house using the House button, and it still had Miranda Docks marked. But then to return to SI (while still hoping to keep my mark), I used my life fountain button which took me to Avery's Court. It removed the mark in Miranda. Why? Aren't the marks supposed to stay if you go to Avery's Court?
Yeah, unfortunately it's very easy to do, but you need to be careful bouncing back and forth between your house and Skull Island when using the teleport buttons. The fountain in Avery's Court will override your previous fountain when exiting your player housing by using the Go to Skull Island button.