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
Have you tried the good old
#update-grub
?