B9S 1.4 cannot see SD boot.firm

[MeatSafeMurderer]

For whatever reason the, as of 1.4, B9S can't detect the boot.firm in the root of my micro SD, meaning that if a valid boot.firm is not already present in the CTRNAND my n3DS XL won't boot and I have to use ntrboot to recover. It also seems to break Luma3DS's chainloading functionality, as holding start will just kick me to the home menu as normal. Downgrading to 1.3 again resolved these issues.

In case it's hardware specific I'm using a EU n3DS XL with a 64GB SanDisk Ultra.