Missing high-end weapon attachments that I crafted, after joining matchmaking. This happen yesterday too with my crafted liberator. But I noticed it and just restarted the game and it was back in my inventory. With the attachments I didn't notice till I went to zoom in and my scope wasn't on. A restart did not fix it.
The attachments are visually on my gun at the character selection screen but whenever the game loads they are not on my weapon nor are they in my inventory.
I hope this helps you guys fix the issue. Just in case you have a log of character actions I can message you my gamertag.