All of the base modules of Mog-It requires a re-do; This does not include the 'Epsilon Armour' ones.
As for the "Why" question, here are my reasoning.
You have multiple entries of the same item.
You have DisplayID headers listed differently than the in-game ones, which confuses the addon.
You have different DisplayModels tied under the same DisplayID header in the modules
You have item-classes outside the scope of the module listed in the module.
You have missing items listed in no modules. (At least, I couldn't find it listed anywhere)
There are entries that are no longer in the database server-side that are causing the addon to cease functioning.
All of the above are in a single module (Cloth: Head) This is a reoccurring problem in all of the modules to some extent.
I personally suggest taking a itemDB sql dump, adjusting it to fit the Mog-it Headers, and then sort them into where they should be. Heck, I'll even do it myself if you want that.
But as it stands, the current configuration of the addon directly impedes/hampers the player's ability to find items that are on offer on Epsilon.; and makes Wowhead a better alternative.
