I'll throw this in the mix. What if the flying conditions had more to do with the clunk out of the fuel? Gusty conditions, the plane getting bounced around, all that. There are times when the clunk is out of the fuel when doing aerobatics, but it never last very long. You take Johan's situation, the plane is low on fuel and being tossed around by the wind. Those forces aren't the normal aerobatic forces. I've been flying when wind are gusting and have seen my plane literally stop in mid air. Nothing you do in aerobatics duplicates this.

Johan, your instructor acted admirably. Landed your plane safely, then let you slog your way through the mud to retrieve it.