Items disappearing from Chest and Backpack.

Title: Moving items out of Backpack into Chest can cause items you were transferring to disappear.
Blocker? No.
Details. Had 3 Pristine Spider legs already in chest. Stacked as 2 and 1. Tried to move 5 Pristine Spider legs into chest. Items did not transfer and highlighted Red in my backpack, eventually they totally disappeared when I tried moving them again. Tried same thing Pristine Bear Head, I believe it was a Patriarch, it also highlighted Red and then disappeared after trying to move it. Other items seem to move ok. Logging in and out brought the items back into my backpack.
Reproduce: Not sure.???

 

We're having difficulrt reproducing this internally. If you could verify the issue is occurring and reproducible, it would help us out tremendously.

 

Attempted to reproduce this issue several times with no luck. Everything worked fine. The only thing I can be sure of was the items turned red in my inventory after I moved them, which they do not do on a legitimate transfer.