Bitlocker PIN rejected after dual-install of Ubuntu with encryption

I have a Thinkpad with Windows 10 installed, with Bitlocker setup and previously working. I've just installed Ubuntu along-side Windows, and I enabled the "encrypt my home drive" option during install. I am using grub as a boot manager.

I can boot into and run Ubuntu fine. If I select Windows from the grub menu, I get to the Bitlocker screen as I normally would, but it no longer accepts the PIN? Is there any recovery from this?