This bug is on our list of things we'd love to fix, but we're having trouble making it actually happen. Have people gotten this with sentinels as well as cats? Does it still happen with no companion equipped at all? Does it still happen if you take all the mods off the weapon? Does it still happen if you're alone in a mission? Does it still happen if you take off your other weapons? I'm hoping that by pooling information from Tenno in the field we can narrow down the cause by process of elimination.