Curios add and remove commands don't work in servers, but work in singleplayer

[IulianDan]

Versions

• Curios: curios-forge-5.2.0-beta.3+1.20.1
• Forge: 47.1.42
  Observed Behavior: Can't use the command to add slots (/curios add belt IulianDan) on server, it says "Unknown curio slot type belt".
  Expected Behavior: Output: "1 slots of type belt have been added to IulianDan"
  Steps to Reproduce:

1. Make a server using the official forge server files
2. Add Curios Api and a mod that uses a slot (I'm using refined storage for the belt and body slots)
3. Join the server and try to use the "/curios add" command
4. It shows error in chat
   The command works fine in a singleplayer world, but breaks when using it in my server despite having OP. It also doesn't show the command autofill suggestion for the slots. Doing "/curios list" outputs "belt - refinedstorage" and "body - refinedstorage" but I can't add (or remove for that matter) any slots using commands.

[IulianDan]

Should also note that I tried to use NBTExplorer to change the amount of slots within my player data (by changing Size in "curios:inventory" to 2 instead of 1), it made the server say I had invalid player data when trying to join. Changing it back fixed it.