Mon function turns on without prompt from user on second receiver and on AM

I am running release 15.13. When I have first receiver set up and bring on the second slice and I switch the active TX to that second slice, every time I transmit the Monitor is active however the MON icon is gray. If I switch back to the first receiver and I switch the active TX to that receiver, there is no monitor unless I click on MON as I would expect.

When I operate AM, the MON function is on no matter which active TX us used and the MON icon remains gray.