Is the Truffle Worm the first bait item in your inventory? I've heard of cases where if you have another type of bait (like a Grasshopper, for instance) in front of the Truffle Worm, it will use that instead. That might be the issue you're having.so fishing in the ocean with a truffle worm doesn’t seem to spawn Duke Fishron...
Hi @Ghastly, are you able to post a screenshot here with your inventory open and where you’re trying to fish. That might help us help better.It was my only bait