am playing on version 19.2009 when colonists store inferno cannons or heavy charge blasters in a stockpile the weapon will instantly disappear and will not be able to be got back
edit: same thing happens when placing on a shelf
I don't think these weapons used by the mechanoids, the inferno cannons & heavy charge blasters were not meant to be weapons given to humans outside of mods and spawning them in dev mode.
They disappear when they are dropped by in any means, except for the charge lance which can be built in the Fabrication Bench in normal game.
Not a bug, these weapons can't exist as items unless you use dev tools or mods.