This bug is going on for 6? weeks and i admit, i am no programmer and i also have no clue about it, but i managed to come up with your "theory" on myself after a few days of the bug. So for me, BW has basically no idea what is causing the bug.
Server Vanjervalis Chain - Advanced Accuracy Augment 40 - not searchable after todays patch, it was before.
Edit: After some time at the GTN, the last restart increased the number of non-searchable items by around 500%.