In the last round of frenzy co-op I played as a machine gunner, whenever I resupplied at the crates (using M then confirm loadout) and switched weapon immediately after, all my weapons disappeared and I couldn't sprint. This would usually continue for a minute and then the weapons randomly appear again. NO amount of switching weapons/moving/jumping around/resupplying again around would fix the problem other than just to wait. This is a seriously annoying game-breaking bug.
Weapons disappear after resupplying