I feel as though my bug is related - I also made myself a dye vial out of a cask of dye (neither of Clara's mentioned colors; I sent a modmail about it due to the name not matching the appearance) and then logged out for unrelated reasons. I later noticed that my inventory claimed I had one more item than depicted (I saw 9 pictures with text but it said the number 10 in my encumbrance bar), thought back, and remembered that I never put away my dye vial.

I just now poured myself another dye vial from the same cask and logged out immediately after making the vial (and clicking 'Look' on it, if it matters; I also did that the previous time because I was trying to check whether there was some funny transparency effect going on with the wood color and the dye color, due to the name mismatch), and my inventory now has 2 more items than depicted.