Could improve -
Occasionally the full volume won't go in at a fill-up.
Spit balling here. I wonder if has to do with the rate of filling and the "back flow" from the aux tank. That is, as the aux tank is full so fuel is going to in but burp back out thus interfering with the filling of the main tank causing it prematurely shut off. Given the issues is intermittent I wonder if the rate of filling was slower there would less interference???