Inverted fuel issue

Hi,
I'm in the process of completing my rv7; I levelled the aircraft for weighing & calibrating my fuel level senders. Having filled and calibrated the fuel sender in the tank containing the flop tube, I then decided to pump out the fuel via the electric pump with hose disconnected into a can. No fuel came out, i then removed the drain and emptied via that route.
I disconnected the line from the tank to valve and squirted some air into the tank.
A dull thud was heard and then fuel came out ! I refilled the tank and fuel flowed as expected.
It's difficult to understand what may have happened, I have removed hatch where the original fuel pickup would have been and inspected inside the tank, all appears ok.
My theory is that the wings have stood in a rack, leading edge down for 2 years, could this have caused the flop tube to fold over.
Any suggestions welcome.

I don't think the flop tube is flexible enough or has enough room to fold over on itself in the tank...could be wrong though. I wonder if it might have gotten stuck maybe on some proseal that hadn't fully cured? While you have the float cover off you could get a good look at things with a borescope before closing it back up. I am assuming the wing is still attached. If memory serves, there is a guide to keep the tube from hanging up on the rib. Ensure it is installed. You want to make sure everything is right with the fuel system!

The flop tube cant fold over itself. Perhaps the weighed end had a cap over it.
Tom