Fighters \ Troopships and supplies

I am using fighters on my troopships when I capture planests. The fighters only have weapons that use supplies and my troop ship has plent of supplies. But when I put the fighters back on a troopship and drop them on another planet half of them have no supplies.

I even tried lauching the fighters from the planet. Checking they were max on supplies then transfering them to the troopship and that seemd to make no diffrence. Any ideas?