Ellison Throttle Body - inverted issue

I have an Ellison 4 on my O-320 RV-6 with a right tank flop tube and inverted oil system. When inverted it flies fine sustained... when upright it flies fine sustained... when righting back from being inverted it starves for fuel for up to 10 seconds or more ... I don't think it is a flop tube malfunction because it occurs even when that tank is TOTALLY full (I mean ain't no air bubble getting into a flop tube from a FULL tank).

It doesn't starve upright or inverted, but seems to occur when I roll back upright after sustained inverted. ???

Has anyone encountered anything that I'm not thinking about here when using an Ellison for aerobatic maneuvers?

Help, Ed Verner RV-6

Which way is the regulator oriented on the Ellison? To the side?

Have you tried rolling both right and left to see it that makes a difference?

Could the flop tube be kinking and folding over at some point in the roll?

Ellison or flop tube

I think the kink in the flop tube suggested by Rob might be a possibility. I hadn't heard of this before. Mine only stumbles occassionally when I have less than 6 gallons of fuel in the flop tube tank. Right or left rolls don't seem to make any difference.
Bill
RV-4 Slider
Alabama

I will do more extensive flight test work after sun n fun, as my bird is at Lakeland, and then I'm thinking possible kink. More soon... and thanks all for thoughts

The EFS-4 is oriented on bottom with fuel flow upward in upright flight.