I got recently the following item and AllTheThings is not tracking it

Name: Disciple's Stein
Item ID: 15932
Equiped on Left Hand
Bind on Equip

Got on Exterior Zones > Eversong Woods > Rares > Eldinarcus

Share transmog with:
Item: Lapidis Tankard of Tidesippe
Item ID: 4696

Thanks for the information! I'll look it up now and get all the info associated with it. At some point Blizzard did something with the sourceID's on items that aren't moggable and I thought I had added them all back in, but missed a few.

Looking at it in-game it should be appearing. You can try a Shift+Click on "ALL THE THINGS" header to have it force a refresh.

Just to make sure it does register I'm manually adding it since it is a stein and could cause issues.

What I mean the stein is on ATT, but the stein after obtaining it ATT isn't mark as collected, is still marked as Not Collected

Yes, if you Shift+Click the ALL THE THINGS header it sends a signal to Blizzard to resend your wardrobe. After that it can verify you have it and properly check it off. If it does, then it's a bug in which just fixed (in case that's it)

Fixed in dd6cc90

Shift+Click also forces a refresh and shows it properly collected.