I just upgraded and didn't have any issues. I'm not experienced in this regard at all. But just to be sure, did you execute the following after the upgrade?
sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi
sudo grub-mkconfig -o /boot/grub/grub.cfg
Assuming of course your grub setup doesn't differ from mine. These two commands are all I know about grub troubleshooting...