Just a heads up that this can be an issue, but I'm not sure how common
it is. It applies to BIOS (not UEFI) firmware, and for systems that
originally had Fedora 20 or older installed and also never had
'grub2-install' issued since then. Therefore it can be prevented just
by running 'grub2-install' before commencing the Fedora 30 upgrade.
https://fedoraproject.org/wiki/Common_F30_bugs#GRUB_boot_menu_is_not_popu...
It's worth going through all the Common Bugs.
--
Chris Murphy