Here's a temporary fix: remove the datapacks from the world, load up the world, and then put the datapacks back in the datapacks/ folder and then reload them.
To reload them, you type "/reload". If you're in singleplayer, you'll need to go to the escape menu, click on "Open to LAN", and make sure "Enable Cheats" is on. Then press "Start World" or something similar, and then type "/reload".
I think this issue has something to do with the fact that forge mods are listed when you type "/datapack list".