"account is requrired" for POS sales invoices

Hi I’ve got a fresh setup of ERPNext with a barebones setup and I’m trying to get the POS system to work. No matter what I do, I keep getting “account is required” when I submit the sale.

If I click on “form view” and click on submit for the sales invoice, I get the same thing. BUT, if I uncheck “include payment (POS)”, it gets created. Does anybody know what the heck am I missing here?

Thx
S