I just did that T with the British Supply. Didn't get a "complete". Maybe because not all the shipping I sent to the bottom were in the BS Zone. Most was but not all.
Is it possible to go into the config and chea a bit and change False to True?

Note tho that I intend to start a new campaign with a clean install of SH5, so some of the mods I want to use will work.
Edit:
But I first want to do the British Blockade patrol to see what happens.... and get a heads up on it.