Ocean Trawlers no longer work unloaded

Trawlers used to work unloaded, getting about one fish per day each. I recently tried using them in an out of the way area, teleporting to them every few days as Wortox.

After checking them 5 times total during autumn and early winter, none ever got a single fish. Their nets never broke, so it wasnt fish escaping. Tried both with monster meat and empty. Their placements also varied, 2 were far apart to see if those would get more, 3 were close together.

Edit: also tried with kelp, and waiting 6 days. Nothing there, either.