Weapons getting "lost" in inventory

PC (Steam)
I’ve got two three-star Möller PP which have gotten lost in my inventory. I can still attach ammo and mods to them, but I can’t retrive it without replacing it with something else, since the guns aren’t either in the inventory or equipped.
Steps To Reproduce:
Picking up three-star Möller PP
Images / Videos:

Host or Client:
Players in your game:
Just me
Intel® Core™ i5-6400 CPU @ 2.70GHz
NVIDIA GeForce GTX 960

The ONLY scope for my .50 cal rifle disappeared from my inventory.

That was just before I went to mount it. So…hours of wasted effort.

I have shelved this game, and consider my $40 a complete scam now.

Wow… That escalated quickly.

Sadly, this happens to me as well with in particular ammo.
However, it’s not like Scopes are rare, dude. Find another one. Jesus…