Okay, it sounds to me that I should change V23 Genre to null separate values like V24, then if Xmbc is fixed so you can specify null as the separator that should work.
In the meantime, how about you take advantage of the fact that Jaikoz can also writes genres to the grouping field, comma seperated. Use Edit/Swap to swap the contents of genre and grouping fields, (or delete contents of genre field and use Append to Left) and just modify Xmbc to use the comma as the field separator