I have the same problem. It's been weeks and my stuff is still missing. In addition to folders being either empty or altogether missing, I have objects that seem to have somehow turned into a folder.. therefor cannot be rezzed. I'm hopeing it comes back. I have alot of missing items that cost lots of time and effort to create, aswell as some that I have paid many L$ for over the years.
=(
okay, Just did a cache flush and it worked like a charm. Everything is back.. Yay!
I'm using Pheonix viewer 1.6.1.1691