Interesting, I didn't realize Lucy is no longer collecting that info. It used to. I assumed since some of the ones I listed are known to not work any more that, they all had been removed. But after checking some on the most recently updated items on the 13th-floor list, they too show no potionbeltslots on Lucy :(
Some on the list though are confirmed to no longer give the potion belt slot, and have very old update / verified times (at the most recent Jul, 2008, some even older).
I should of looked there first anyway, but just assumed the Lucy db still collected that information, since it used to, and the attribute is shown on the items raw data. Oh well, live and learn :)
Yther Ore.