Just after sending my previous message I noticed the following versions were available after an apt upgrade:
grub2-common 2.12~rc1-9 grub-common 2.12~rc1-9 grub-efi-amd64 2.12~rc1-9 grub-efi-amd64-bin 2.12~rc1-9 grub-efi-amd64-signed 2.12~rc1-7 so I bit the bullet and made an upgrade. It works. The computer boots normally. The only thing I noticed is the grub screen saying version rc-1.7... Shouldn't it be version rc-1.9? Anyway, it works. Thank you!