I had the same issue and also resolved it with spray lube. I also lubed the flap hinge as well👍

 

I had this problem on Saturday. Unfortunately, couldn't open it. Called AA. Flap was opened with me pulling the lever and the patrolman applying pressure on the flap and using a screwdriver when partly open.
Problem was the bottom part of the plastic catch had broken off. Now driving round with flap partly open until I can get a new catch fitted.

This area has been the bugbear of my problems. I cannot put any autogas into the tank using the adaptor. I have pushed the ball bearing down, but as soon as I attempt to put the LPG in the ball bearing seals the hole again. My next attempt will be attach a metal skewer to the bar on the adaptor and for the pointed part to push the ball bearing down and keep the hole clear. Finger crossed!

 

I never had a problem w/ it, but I took it apart as it was incorrectly installed!

The round plastic cover is fixed w/ a single screw in front & abuts against a blob of welding at the back. It has a plastic tab also. There is a spring inside & the mechanism has to rotate. The tab is seen towards the bottom of the 2nd pic & it has to be inserted into the steel panel. The cable can also be seen around the right edge in the photo w/ the end cap positioned under the screw end. I greased it & replaced it.

I must say the design is poor, likely to break & this simple job took me some time.

The 1st Pic shows the unit after replacement (correctly intalled) w/ the carpet pulled aside. The 2nd Pic shows the internals before greasing.

PS: The cable can be accessed from the top of the area where the jack is stored.

 

Reference your LPG filling issue.
The ball bearing seals the tank and the pressure of the incoming gas should cause the ball bearing to unseat and allow the tank to fill.
If you attach a metal "skewer" to the bar of the adaptor it will displace the ball and allow the gas in the tank to escape when you screw the adaptor in as the tank is under pressure. This would be highly dangerous!
LPG is not like petrol which is liquid at ambient temperature. LPG is only liquid when under pressure and revert to gas when pressure is lowered so the ball serves a vital function of maintaining the tank pressure.
I am thinking that the pressure of the filling station LPG dispenser is too low to displace the ball bearing so I suggest you use a different filling station and also inform the staff of the filling station you have been using of this issue.

 

Metal skewer, metal filling nozzle, explosive gas.. what could possibly go wrong.. 🤣

 

I had this on a sandero in the middle of rural France in the last open petrol shop on a Sunday!
I managed to release it by pulling the flap open whilst someone pulled the release. In my case it looked like the flap was mis aligned. Even though the paint indicated it had never been moved!
I slackened down the two Hong bolts and re aligned it - leaving an equal gap all round.
Why after three years it should suddenly move is beyond me!