Same here, this happened to me once about two days ago. I was riding the nimbus from Guild City and just before I went up the stairs there was a flash and all of my equipment was missing. A quick log reset the issue.
Although, I am not sure if it is the same issue, but a party I was in was farming the Tradu Crypt and just about everyone in the party experienced a similar issue where after entering the Crypt all of your equipment was missing. No flash though. Not everyone experienced the issue at the same time but it did happen more than once and to more than one person at one time. Again, a quick log rest the issue.