More confusion.....
I was on a Combi 747-400 (KLM) last night... Both APU Generators were selected ON... and there were no problems with loading (or should I say no electrical problems.... the drive system was so powerful, the cargo was punching holes in the sidewall panelling). I guess this aircraft would only stop loading if there was loadshedding (as opposed to some kind of aircraft logic stopping power going to the cargo (at all times) if APU 2 or EXT 2 was selected ON).
Cheers.
Q.