I'm experimenting with a 2014 macbook pro upgraded to macOS 14.4 (Sonoma) with OpenCore Legacy Patcher, Linux Mint 21.3 Virginia and Linux Mint 21.3 Xfce.
First, I installed Linux Mint 21.3 Virginia and I could boot both to macOS and Mint. Then, I created another partition and installed Mint Xfce on it.
Now, I can only access both linux operative systems and macOS has disappeared.
What I don't understand is why now the notebook boots directly to grub instead of booting to OpenCore Legacy Patcher
you've got a grub bootloader in the efi partition. the computer is booting the efi partition's grub straight out of the gate. it doesn't know about the macos so it can't boot to it.
you can edit the grub config to put an option in to boot to macos from grub but you can also just use option-boot to select partitions when you power the computer on.
option-boot is when you hold the option key when you turn the computer on.