I am changing the slot_id's of Trinket's default slots, but the changes only apply after /reload is ran.

Here are the affected files:

data\trinkets\slots\head\group.json
data\trinkets\slots\chest\group.json
data\trinkets\slots\legs\group.json
data\trinkets\slots\feet\group.json
data\trinkets\slots\offhand\group.json

The ID's I changed:

head - 5 -> 78
chest - 6 -> 79
legs - 7 -> 80
feet - 8 -> 81
offhand - 45 -> 77

Before /reload is ran (slots do not work):

After /reload is ran (slots work):

/reload has to be ran every time the player enters the world.

This seems like some very peculiar data loading issue, Trinkets has no special casing for slot ids and everything is read from json, so I'm not sure what could be requiring a reload, have you tested different ways of providing these files like with a mod datapack/world datapack/editing trinkets?

My initial test was through a mod-datapack (you can see the commit here: Andrew6rant/LittleBigInv@fa8988a). I then tested with a regular world datapack, and I had the exact same issue. Editing the Trinkets mod itself also led to the same problem.

But, now I think I know what is happening (and it is my fault, whoops!). It's most likely related to the way BigInv replaces slots. Specifically, armor and offhand ones.

At first I thought it was happening for slots outside of Vanilla's default range (45+), but then found out that this only breaks with EquipmentSlots. If I make a mod datapack/world datapack or edit the mod to change the slot_ids to be: 78, 79, 35, 12, then 35 and 12 will show up fine but 78 and 79 will need a /reload to appear.

Oh that's very peculiar, but I believe outside of the scope of Trinkets, so I'll be closing. Best of luck with screen handlers, they are prickly