I've noticed that the savedvariables for this addon has multiple variables in which the saved outfits are stored, however, in each one, they're stored slightly differently, and I can't find rhyme or reason for where each one is used.

The best way forward may be a new variable, that will be the only one outfit data is pulled from, and an interim addon-version which will go through the current existing variables, and populate the new variable's data. (It could check the various existing variables and pull in the data from whichever can satisfy it.)

That actually was done last update which is why it took a while to get out since I had to make a lot of adjustments to get everything in sync. The reason you see a lot of similar variables is that the data storage has gone through a bunch of adjustments over the various versions and the savedvaribles files will continue to store the old versions unless it is specifically erased by an addon.

I'm still having a number of the issues that trace back to this, such as the dress model in the thumbnails for new outfits being naked.

Sorry, should probably clarify there. It's the interim sets that were made around version 3.5.

Those don't load at all anymore, and the thumbnail model is naked, but the name of the set shows up, so it's loading from some incomplete variable that wasn't fully populated. Reverting BACK to 3.5 allows those sets to load, so the data is definitely still present and not corrupted or overwritten.

https://gist.github.com/Ketrel/aabc56041c445f4c105bcd6672f4c00a

I made all the names/servers generic so the only thing I'm revealing is my secret item combos and corny transmog names haha.

Anyhow, the toon in question is "Toon-Paladin-Main" and ones exhibiting the issue I was referring to are outfits 55 - 65,

Thanks for the additional info, could you possibly dump the saved variable to a pastebin so I could look at the data. I probably dont have that version in my various old savedvariables files.