I didn't get the Fire Axe that was supposed to be unlocked.

Product: 戰地五世
Platform:Sony Playstation 4
Please specify your platform model. Sony PlayStation 4
Which part of the game is the issue happening in? Multiplayer
Which part of the mode? Firestorm
Please select your region Asia
On which server did this happen? PS4
When did this happen? (dd.mm.yy hh:mm) 2019/4/13
Summarize your bug I've completed the weekly challenge, but I didn't get the Fire Axe that was supposed to be unlocked.
How often does the bug occur? Occasionally (10% - 49%)
Steps: How can we find the bug ourselves? Check team equipment field
What happens when the bug occurs? didn't get the Fire Axe that was supposed to be unlocked.
What should be happening instead? Unlock the fire axe.

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I've completed the weekly challenge, but I didn't get the Fire Axe that was supposed to be unlocked.