Westfalia tow bar fitting issue

[Horrgakx]

Apologies for posting here, I've got nothing so far from other forums.
I have a detachable Westfalia tow bar but as much as I try it just won't go in.

Here's a video. You'll see I also try rotating the release knob and also the key but it makes no difference (sorry for the drilling noise in the background, I used a noise gate to try to reduce it).
https://youtu.be/f7vSAtzBc34

It SHOULD go like this, which looks very easy!!
https://youtu.be/UsCf4PDe1PY?si=bgeMTEOJPzkNSpkc

(PS - to the admins of this forum, the Tags section needs 3 characters minimum but that means you can't add the likes of A3, A5, A8, etc....)