Minecraft 1.20.1
Forge 47.3.5
EMI 1.1.19

Observed Behaviour

When adding an item tag to a list of items using resource pack recipes (not data-driven) only the first item in the tag is listed. When left-clicking the item, it pulls up the recipes for that item, rather than the tag list. When right-clicking on items in the tag to see their recipes, the resource pack recipe in question does not appear.

Expected Behaviour

The tag appears in the item list, or at least all the items in that tag appear in the item list.

I'm not fully clear on if you're talking about the index or recipes, but tags cannot appear in the index and recipes always support tags, so this is currently working as intended.

Let me explain. Here's my JSON file, which I've added a tag to:

The whole output of this world_interaction entry is enclosed in square brackets, indicating a list of items. I've added a tag to that list. Just to illustrate that this is a valid tag, here's that JSON:

And here's how it actually shows up in JEI. It's not a tag, but an item. As described above, it acts exactly like an item.

Outputs in recipes cannot be tags, they need to be deterministic

I see, so this was a design decision rather than a limitation. In vanilla loot tables, results aren't deterministic. Items in a tag are chosen at random. With this restriction in place, it's impossible to create custom "loot table like" world interaction recipes. Sluicing is actually an excellent example.

Please reconsider this design decision. As far as I understand, it wouldn't be that difficult to fix.