I have Ubuntu only on this computer and when I check with gParted your suggestion regarding ESP, find I only has the boot flag active.
This post is regarding : How to Actually Install Ubuntu on USB
Previously this was a Win10 machine. Fast & Secure Boot are disabled.
Any advice please on how I might fix this issue. Ubuntu did install a 512 Mb fat32 partition for /boot/efi/ as mount point. The rest is an extended partition with the ext4 partition in it, and a swapfile in root.
In my BIOS the CSM shows Boot device Control set to UEFI & Legacy. Also has Boot from Storage Device set as Legacy only.
Much appreciate your comments and assistance.