This happened to me as well. I submitted a bug report, but what happened to you sounds pretty similar to me in that it happened while mining banite ore. I saw a reddit post regarding it as well but there doesn't seem to be anything else besides this thread.
My box was a bane ore box, however. I was mining in the glacor caves and suddenly noticed that my inventory was full and the box was gone. Kinda sucks cause I lost 90 some banite ore but really not that bad.