Possible Fixes

Yes

Modpack Version

All the Mods 10-2.8

What happened?

If you try to add more curios slots with /curios add (tag) (player) nothing happens. This is already a reported issue on the Adorned (Curios) mod page.

SOLUTION: Remove mod Adorned (Curios) and replace with Curios API continuation.

This will fix the commands and nothing will be broken. I just did it for myself in a new instance and it works flawlessly.

latest.log

No response

Developer reports

No response

Suggestion to swap mods was brought forward to team and then promptly denied

Curious commands not working is a duplicate of #327
Adorned dev is aware, and suggests that you do the change in config instead