Hi, I reached out to our partner and here is their take on this function:
"This function is meant for customers using Billing Schedules on their Sales Orders. You are not using billing schedules (and are not able to as billing is based on fulfillment happening), so the invoices would not be picked up in the bill run process. Also this is meant to be a set day that billing is run and cannot be past the 28th of the month, this would not work for Intercompany and you need these generated through the end of the month to make sure accounting closes properly. This function also does not allow for usage on the vendor side at all (so no VBs or POs)."