Items with suffixes, i.e. shoes 'of the tiger' or 'of the bandit' tend to lose their stats at some point when playing. For instance, my druids Feral Shoes of the Wahle used to have spirit and stamina on them but now they only have 57 armor and no stats. This isn't just a visual bug, if you equip an item that';s supposed to have intellect like 'of the owl' equipping it won't give you more max mana.
I know this has been going on for a while, I've seen items in auction house with their stats missing but I've never known what causes it. Is it intended or a bug? Is it caused after a certain amount of days? Just curious. Always known about it, but it's only ever much of a bother when leveling a character.
I haven't seen this happening for years now. I think you should delete your Cache folder. Anyway, although it seems like you lost the stats, the server still calculates everything with the proper stats. just don't worry.