Yellowing fan out of nowhere. Looks like I’m gonna lose this one. Anyone have problems like this? It’s normal to lose older leaves but a whole fan is something fishy
I have had older fans die more often than losing individual leaves from them. If you haven't recently repotted, might be time to unpot and make sure that there isn't anything systemic going on with the roots.
I'm no orchid expert at all, but I do know a few things about plants. I wouldn't be surprised if it's what RJSquirrel said in that the plant is killing off some leaves.