I don’t press the release button as I’m plugging in. The locking pin will not stick down unless I push with substantial force and hear this loud click. I have no issue with it releasing very easily after I am done charging.
One of my dumb chargers at home has a tight fit compared to some other level 2s that I've used. I sometimes cant get it to click nicely though it still charges. I just assume it's the connector being slightly big and notca problem with the car.
I find that it’s easier it connect with the button pressed. It lowers the pin and makes it go in easier. I think your locking pin is a little stiff and/or the approach angle of the pin or the shape of the pin head is a little off.
having said that, my pin is broken so I don’t even bother with the button anymore.
Use some dielectric grease on the the connector. Apply a liberal amount to the plug holes where the contacts are. apply some filling the holes then plug it in and out a couple of times. put a little more and plug in again. Finally remove and wipe away the excess from the ends of the plug and car side. This will lube up the connector. There is rubber insulators that are making it difficult to insert. The dielectric grease will make it much more easy to insert and also keep the contacts from corroding. you will be amazed on how smoothly you can connect after you do this.