Lost Rare Items 2x from Epic Container Purchase

Twice this week I have lost Rare Weapon combo items after purchasing Epic Containers. Both times it has occurred when I had 2 partial combo items from scrapping and both times the lower totaled item disappears from my inventory. The first occurred with a 9/10 and a 6/10 box when the 6/10 was lost and now I had an 8/10 and a 7/10 where the 7/10 disappeared. I am not even sure why there are 2 partial boxes to begin with since the first one should fill 10/10 before another one begins. Now I am wondering if something similar could have occurred with epic boxes and I just missed it.