For some reason, and I have no idea why, certain items do not match the difficulty conversions bundled with the add-on. This causes these items to not show up in the tooltip(s) as BestInSlot, nor equipped.

You can find these missing difficulties yourself by adding print(instanceDifficulty) to Core.lua:592 (above local bisId = self:GetDifficultyIdForDungeon(instanceDifficulty, item.dungeon, true))

The Additional M+ difficulties I've found are the following:

	difficultyconversion = {
		[1] = 1, -- NHC
		[2] = 2, -- HC
		[3] = 23, -- Mythic
		[4] = 35, -- Mythic+
		[5] = 8, -- Great Vault
		[6] = 33, -- Additional M+ #1
		[7] = 16, -- Additional M+ #2
	},

It would be fantastic if you could release a new update with these additional difficulty strings so this add-on can continue to work for everyone.

Thanks!