1 - Create a file named startup-manager-fix.service with the following text:
Description=Show EFI Install in Apple Startup Manager
ExecStop=/bin/cp -a -f /boot/efi/EFI/ubuntu/grubx64.efi /boot/efi/EFI/BOOT/BOOTx64.EFI
It's because MacBook's native bootloader looks for .efi files inside all internal and external HFS+ partitions.
Necessary conditions are...
there is a partition formatted as HFS+
the partition contains the partition id af00
in the root of that partition, there is a file called mach_kernel
inside that partition, there a boot.efi file inside /...
I'm not sure if you are comfortable trying to use the command line, but this is a known issue on Linux with some Apple keyboards.
This Arch Wiki Page has instructions for fixing your exact situation. Please try this, and let me know if you are successful.
System setting. Then in system setting go to to keyboard. This is where you change your shortcuts
Go to custom to make your own shortcuts
If my explanation are terrible just check the image below :)