When i reached a certain level like 15 and 20, in the level up screen it shows that i will get a mythical and a gold chest(correct me if im wrong) but when i reached that level, they will reward me with the sm and 10 T but the game just hangs afterwards and i have to restart the game. And when i go back, nothing pops up and there isnt any chests at all/ new items in my inventory, and when i level up after finishing a campaign( levels 15 and 20) and opening chests and getting like 200xp and receiving the level up notification, the rest of the chests dissapear because the game hangs after they give me the sm and 10 T. I've lost 2 chests so far and about a few boxes from quests(idk what you call those). Please fix this !

I have the same isse. What i have to do?

Bump.

From my experience, you actually receive the awarded items, but when lvlup window pops up on lvls 15, 20, 25, etc, there is no "OK" button which usually closes that window. The only thing you can do is kill the game and log back in.
By then, awarded items will already be in your inventory.
You don't get chests, just 1mythic(lvl15)/1legendary(lvl20)/2legendaries(lvl25)/1mythic(lvl30)

Same bug. Got level up to 30 after campain mission. Saw mech goes to number 30 and 2 chests. Then game hanged and disconnected. After relogin - no chests and no misdion prises.

^ This is spot on.

Sorry for the issue guys, we're still pushing this fix to some platforms.

The item still end up in your inventory

Just hit lvl 30 and "OK" button popped up, didn't have to restart the game.
One thing though, I didn't see what item I got as a reward (lvlup was in the middle of the mission), but rather, a window popped up saying I have new equipment options diplaying 3 Leg part SLOTS, not PARTS.
After finishing mission, I went to workshop and saw new "Flame Legs" part.
I could hardly be happier

Currently using Microsoft Edge to play

This has happened to me before. It's nothing serious, but it can be annoying, because many times I have to refresh the page, and sometimes I have to switch browsers (Chrome to Internet Explorer, and vice versa). However, it hasn't interfered with actual gameplay (except once and that was when my rewards were doubled ).