Bug report for loot box

I’ve received the legendary loot box from the battle pass, but as soon as I opened the box, the game started, so I didn’t get to see what I got.
After the game it showed me what’s in the box, but there was nothing. It was just a black page.
I thought there’s some error, so I just clicked esc, and now I can’t find what I got.
I’ve also checked every single hero if there’s any new item that I got, but nothing got a new item.
So I’m wondering if I can’t see it because I received the item that I already had, and if it’s possible to check what I got.

Also, this is my second account, and the loot box bug happened on my first account.
I have no idea why it’s not letting me to report a bug on my first account, but only second account works, so I’m submitting it thought second account.
Please contact me to fix these.
Thank you,