Nightingale Legacy Portal
In the Desert Herbarium realm, I parasol glided to the top of the Fae Tower and defeated the mobs up there. The last puzzle core didn't unlock so I went to the bottom and worked my way up as per usual. Get up to the top and it still won't unlock despite no enemies spawning.
I can use the Realm Card machine, but I can't complete the Fae Tower to get the waypoints on the map.
Update: Briefly logging out will not resolve this, but I logged out for a longer period of time and the mobs did eventually respawn.