This isn't exactly the same issue since - as you say - sometimes logging into another viewer OR in the case of the current 'missing outfits' problem someone is having, logging in with the same viewer but from a different computer - gets the items to appear again. A few years ago (two or three?) there was a huge rash of reported problems and eventually The Lab agreed that there were issues. It may be the 'cloud' or it may be something else. Overlooking the received folder issues which wasn't my problem of late and doesn't sound like yours either - there definitely is something going on (more than normal) :D. Should I be worried that SL is slowly eating things I've bought? Tried logging on the SL viewer and some items were restored, but the item count went down AGAIN. I'd love to know why my item count keeps going down and then root folders are missing items that I know I have. And yes, I did try typing in the EXACT name of the item (many tests) and search didn't find them. So things can be broken and plenty of people won't even know. For me, all the conversation about groups not working means little because I never do anything with groups but put my tag on to get gifts or to rez furniture :D. Most likely a lot of people have it but don't notice it. Not sure if that is what is happening to you too but I can't believe I am the only one with the problem. It is just a problem with inventory search. I can find them by looking through my inventory by hand. Sometimes yes and sometimes no, but I have proven to myself over and over again (this from a few months back when I was doing all the 52 colors posts ahead of time) that the items ARE actually there. What appears to be happening - again for ME - is that inventory search isn't working well any longer. If so, it 'may' THEN be there when you log back into your default viewer (this is a newly found phenomena for ME anyway). You can try logging into another viewer (Linden if you are using Firestorm) and see if the item is there. Search (Firestorm anyway) doesn't search the RECIVED folder at least for me - so that can be a problem. A couple of things if this is not the 'empty folder' issue which is covered in the link Marianne posted. I agree this has been happening a LOT lately.

An example is I knew I had a 'Follow grab hug HUD' and was going to hug a friend with it to find it NOT in my inventory when I know I had the item. This is driving me crazy with not knowing what I have missing from my inventory to have to get it redelivered. This has been going on for some time but when I try to find something in my inventory I know I have and cannot find it, I have to go back to the marketplace history and get the items I'm missing redelivered(IF I bought it off the marketplace!).

My chimeratool keeps disappearing