In my post #3 you can see a groove that goes around the upper portion of the rubber conduit end, this groove has the trunk steel fit into it and is a pain to get seated. In your post #11 you can see this groove, so it is not obviously sealing the hole in the hatch steel.
This may or not be your problem, but you should not be able to see this groove. This part of the rubber conduit is more or less identical to the other end of the conduit which has a groove as well and should fit like a grommet, partially inside the hatch body just like the other end of the conduit.