I can move an iSCSI LUN to an FC Initiator, but not the other way round

I created a mixed protocol initiator, and mapped a LUN that was previously mapped to an initiator with an iQN.

Now this mixed protocol, I have added FC WWNs.

I tried to revert to the earlier initiator, and discovery failed on the server.

Is it a thing with NetApp FC Protocol even when you specify the mixed protocol, or there is an extra configuration I must enable in the iSCSI initiator?