MacbookPro keyboard not enabled during boot up

I've got LUKS encryption set up, so every time I boot up I have to enter my hard drive password. However, I've found that the MacbookPro 2015 built in keyboard is not functional initially, even though it is a USB keyboard internally that hangs off the Broadcom device. So to unlock the hard drive I have to use an external keyboard. Anyone know how I can fix this? After boot up the built-in keyboard works.