So, here is what I found. Apparently the actuators in the doors sometimes seize up. For me, only my front passenger door stopped responding.
I took it to BMW and they sold me a set of actuators for $105, plus $325 for labor.
They only installed the one that needed fixing, so I have an extra one in the trunk in case the other one goes.
It came to $460 or so total. I wasn't going to spend the cash, but I figured I was already in for the oil change, and I might as well get it taken care of.