The most likely answer is that the wet-sumping is normal.
The AVL has no seal around the crank at the timing cover, and drains the timing cover into the sump when the bike is stopped. Also, the gear-type oil pumps also allow drain back from the return line into the sump, because the gear-type pumps have no seal to prevent drain back.
The engine is intended to clear the sump with its strong scavenging from the gear type pumps.
However if it is fouling your plug, it might not be a bad idea to check the rings to see if you have a broken one, or something.
But, before doing that, it would be advisable to check/clear all the hoses involved in the engine breather circuit, because a clogged breather will cause high crankcase pressure, possibly un-seating the rings, and allowing oil to pass by the rings.