Most of my datapacks is reported to not work specifically in Realms. This is also the same for others' datapacks.

My datapacks works well in both singleplayer and multiplayer servers. But when you put it on Realms it broke. This also happens to most of my other datapacks, and I had no idea what happened.

Here's the download link for the datapack in particular. Custom mobheads loot table don't load. (Vanilla loot table mobheads do load though.)

https://www.planetminecraft.com/mod/decapitation-more-mob-heads-1-14/

Here's the link to my projects list. Most of them broke when you put it into Realms.

(All of these worked in Singleplayer and Multiplayer)

https://www.planetminecraft.com/member/thediamondplayables/submissions/?morder=order_latest

EDIT: Main reason might be due to Realms deletes certain files within the datapack itself for unknown reasons. Some of Decapitation's loot table files are missing (This also happened in zipped datapacks). Others are folders that has "world" in or a part of its name, which is then converted into the realm name when uploaded, breaking the datapack's functions entirely.