No fish/squids/passive mobs are spawning in ocean

Ocean 10,000 blocks from spawn, seems to be a loading issue after visiting many oceans.

I've been using nether portals to travel far from spawn and found a coral reef at x=-10000, but the entire ocean around it is completely devoid of passive mobs. I waited for several in-game days, swam around, there's nothing. Other locations traveled to in the same way has plenty of fish. I think it's affected by the amount of oceans I've gone to previously (15+ different oceans through portals, at least 2000 blocks apart). I went to the same location in a new world generated by the same seed in creative and plenty of passive mobs were spawning then, so it's not a distance issue. No underwater hostile mobs seems to be spawning either ~300 blocks around the portal, swimming even further away into newly generated chunks generate hostile underwater mobs but I can't find any fish. Above hostile mobs are spawning fine even in the completely dead area around the portal.

screens: https://imgur.com/a/NSV5EIP

Seed: -5279747197756690781

Edit: Exiting and restarting the game within the affected area makes the mobs spawn again.