Yeah, Mac’s are tricky. We do have a UEFI bootloader (which seems to work better in these situations), but it isn’t build as part of the image yet. (nor do we have an automatic installation process if you’re installing to your machine)
@jessicah is working on that, but didn’t make the r1beta1 branch. We still have some hope thought she’ll finish it up before R1 beta1 is released.