Missing item?
 

I was trying to find the Harmonic Hauberk, but was unable to do so. I had no trouble with the other 'focused' items from Grand Bazaar, but this one is eluding me. Anyone tell me what it's under? Thanks!

It's found under armor. I didn't have a problem finding it. It's uncommon, so won't show if you're hiding more than errors.

I looked under armor during my initial search, with 'Hide Nothing' selected, and it wasn't/still isn't there.

That is where it's at. It sounds like you've found other Grand Bazaar items, so the source book must be enabled for the character. In addition to "Hide Nothing," are both checkboxes unchecked?

My eyes glanced right over that top box like it didn't exist. Thank you much!

It happens to all of us at some point! Glad you found it.