Rather frustrating....

A mission weapon disappeared, thats the bug right? You gave no explanation and instead linked to a muted video

There's audio in the video, it's just very very low.

So your mission weapon disappears when playing in a friends game but not when you're alone, isn't that because it's giving you the quests he's on and he may have completed the quest that gives you the weapon or he isn't there yet... hell IDK.

The only bug I got was a bug where I keep dying when I take damage, also when I mark guns as my favorited or trash and then scroll with my mouse wheal, it deselects them. I have to exit out of the menu for it to take.

See how above the weapon it says MISSION WEAPON. That means you only have that weapon for that quest then its gone. If you join a friends gameand he already did or didn't start the quest you won't have that weapon.

If you want to discuss an issue you have with a game you are going to need to be a little more descriptive than: "here's a video, figure it out."

It sounds like your problem has already been solved, anyway:

@TheDoorman said:

See how above the weapon it says MISSION WEAPON. That means you only have that weapon for that quest then its gone. If you join a friends gameand he already did or didn't start the quest you won't have that weapon.