Have you tried looking at the fuse box in the engine compartment as opposed to the one behind the glovebox?
Engine compartment fuse #9 - it’s referred to as ‘engine’ in the
Leon Mk3 owners manual, but the Golf Mk7 is a bit more specific.
However, as above, the fact that the diagnostics is pointing to plug #3 would indicate that it’s a plug/wiring/earthing fault and not the fuse.