Not earning XP for Selbstlader 1906 since 5.2 Update

Product: Battlefield V
Platform:PC
Please specify your platform model. PC
AMD or Nvidia Model Number NVidia GTX 1080
Enter RAM memory size in GB 32 GB
Are you using any software with an overlay? No
Which part of the game is the issue happening in? Multiplayer
Which part of the mode? Conquest
Please select your region Europe
On which server did this happen? All German Servers
When did this happen? (dd.mm.yy hh:mm) 06.12.2019 18:00
Summarize your bug No matter how many rounds and how many kills using the Selbstlader 1906, the XP for this weapon stays at 0. So I cannot earn XP for the Selbstlader 1906. Earning XP for other weapons works. So it seems to be a bug only with the Selbstlader 1906 (the one which does 2 shot kills on any distance).
How often does the bug occur? Every time (100%)
Steps: How can we find the bug ourselves? First of all, install update 5.2. Not sure if you can reproduce it with another account. But you could try to unlock the gun (I bought it with company credits) so that you have 0 XP on the weapon. Then try to get XP for the weapon by killing people in the game. In my case, the XP does NOT increase and stays 0.
What happens when the bug occurs? The weapon XP does not increase and stays 0 making it impossible to unlock specializations for the gun.
What should be happening instead? Weapon XP should increase as it does for any other weapon.

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No matter how many rounds and how many kills using the Selbstlader 1906, the XP for this weapon stays at 0. So I cannot earn XP for the Selbstlader 1906. Earning XP for other weapons works. So it seems to be a bug only with the Selbstlader 1906 (the one which does 2 shot kills on any distance).