Umm if it's a power supply limit, and a 12car can have 2 pans up, then simple physics means an 8car will draw less power overall, as it is lighter, and the same maximum power controlled by the on borard traxction kit, therefore an 8car could have two pans up if it were power alone.
But 8car is limited to 1 pan.
So I suggest it must be another reason, such as pan spacing, and, with the 75 mph limit, I'd suggest the OLE is not yet set up in it's final 110 mph condition, which is probably a very last stage, when the wholelot is complete.