[ubuntu] Unable to get grub menu to show

Hi!:

Recently upgraded from Ubuntu 18.04 to 20.04. Everything has been working OK except that I'm not able to make the grub menu to appear. I've tried hitting ESC, SHIFT keys when booting without success. Is there now a new way in Ubuntu 20.04 to make the grub menu to show? Following, the information about my system:

williepabon@williepabon-Macmini:~$ uname -a
Linux williepabon-Macmini 5.4.0-52-generic #57-Ubuntu SMP Thu Oct 15 10:57:00 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
williepabon@williepabon-Macmini:~$
williepabon@williepabon-Macmini:~$ lsb_release -crid
Distributor ID: Ubuntu
Description: Ubuntu 20.04.1 LTS
Release: 20.04
Codename: focal


williepabon@williepabon-Macmini:~$ grub-install -V
grub-install (GRUB) 2.04-1ubuntu26.6
williepabon@williepabon-Macmini:~$


Thanks for the help.