There is an ongoing post about this in the bug forums:
This happened to me about two weeks ago and has thankfully been fine ever since. Still unknown of what caused it.
I haven’t heard of a followup from blizzard. A ticket I posted back then, it was stated they were aware of the issue and is currently investigating. They can’t compensate for any lost items at this time because it’s very likely it’ll cause more issues than it already is. However that doesn’t mean they can’t compensate for something in the future, assuming this gets fixed.