[Dizzy_Bob]

I stumbled across the carrier in the western mouth of the channel while I was doing the "100000 ton" mission. Not knowing that this was a target of the blockade mission, I tried my luck and managed to sink that beast.
When I then started the blockade mission, the white bar of the carrier mission goal was already at 100%"! So obviously, the carrier has been counted as "mission fulfilled" although I had not started this mission yet

Same here