Yes, has had it before but not so much as now, character is DD and tank and switches a bit and can be the dressing room changes.It's actually an old issue. When it happened to me, the weapon on the opposite bar showed up beneath the feet of the character. In other cases the weapon wasn't really invisible, but wrong animations were applied to the weapon's light/heavy attack.
It's annoying, but can easily be "fixed" by equiping the weapons again.