Would the weather have anything to do with it? with it being hot?

Was doing it before the hot spell

Ahhh right

so is there an update of this issue please and has it solved the problems as in previous posts ,,,ta

Replacement filler cap has solved the issue for me completely - can only assume one which was on there wasn't working properly. 2011 SD4 HSE Auto
(Previously 2007 TD4 XS Manual)

I had the same problem with my petrol i6 model
I knew what the problem was immediately

Petrol cap valve was stuck

Easy fix
Remove the filler cap and grab a couple of flat blade screwdrivers

Separate the white from the black plastic of the cap
By levering the whit plastic past the black plastic tabs it simply separates into two pieces

With a small screwdriver push from rear in centre of the white cap where the valve is
Mine immediately clicked free from its stuck shut position and by pushing screwdriver from opposite side you will feel the valve moving against the spring as it should do
A little shot of anti seize grease to stop it sticking again

Click the white plastic back to the black cap and your done
I haven't had any vacuum build up over the last four tank refills - FL2 3.2 i6 - There is no Replacement for Displacement

If my wife ever sells my stuff for what I told her I paid for it, there will be some bargains out there!