So the one ship blocking passage really is a problem...
I successfully invaded Eastern Germany. Unfortunately, there was a lone CL in Kiel and when I was done with the invasion the CL was ejected. Now I have four task forces that can't move because of that CL. Each one is 3-BB 4-CA 24-DD. More than enough to make Swiss cheese out of a lone CL.
Furthermore, the CL can't move because it is blocked by all the BBs.
Then because the tonnage logic seems to like to pair like sized vessels in meetings, I haven't generated a mission to sink that thing in four turns.
ETA: I "fast forwarded" until March of 1953 at which point peace broke out, but still couldn't move the ships and still no battle. I tried bringing in my own unescorted CLs to try and force a battle, or change my TFs from sea control to something else. Nothing....just stuck.