Changing already-assigned IP Address to FHRP group silently ignores change

[candlerb]

NetBox version

v3.1.1

Python version

3.8

Steps to Reproduce

1. Create an IP address; assign it to an interface
2. Create an FHRP group
3. Navigate to the original IP address and click Edit (i.e. go to /ipam/ip-addresses/NN/edit/)
4. Under "Interface Assignment", notice that it's currently assigned to a device+interface
5. Click on the "FHRP Group" tab
6. Select the FHRP group created in step 2 above
7. Click Save

Expected Behavior

The IP address should now be assigned to the FHRP group, instead of the interface

Observed Behavior

A green box pops up saying that the address was updated; but it is still assigned to the interface, not the FHRP group.

Workaround: When you go to the "Interface Assignment" tab, under "Device" click the (X) next to the device name and interface name to remove them, then go to the "FHRP Group" tab, then select the FHRP group.

I think what's probably happening is that the form is submitted with both device/interface and FHRP group selected, and the server silently takes just the device/interface. If so: when you make a selection under "FHRP Group" (or indeed any other tab), it should automatically deselect anything in the other tabs.