Can't believe it still hasn't been sorted out as it only requires 1 train to be taken out to free up the red signal!
There is no blue path on the map for me. I don't know if taking one train out would fix it. The train wouldn't know where to go in its current state.
The preserved team are currently working on Long Island Rail Road, after which they're moving onto Rapid Transit and Main Spessart Bahn. I would imagine we might not get a fix for this until they start work on this route, which will be a little while yet.