[sublynx]

IIRC, Late war sensors should only be installed really late in the war. If installed before snorkels are around, there could be trouble. I haven't played GWX in a long while, so maybe someone else can confirm this?

Another potential solution, have you changed anything in the data/submarine folder or its' subfolders? Logically the problem should be there, as your type II's work, and everything else works, but type VII's don't work.