Use in-transit encryption unticks when availability domain is changed

In the Cloud Console, when I open the page to create a new compute instance, "Use in-transit encryption" at the bottom of the page is ticked by default.  

However, when I change availability domain using the buttons at the top, "Use in-transit encryption" becomes unticked.  

I believe the "Use in-transit encryption" setting should stay unchanged after the availability domain is changed.