Hi,
FOR YOUR INFORMATION
I used a linux mint 22.2 XFCE iso and extract edeverything using xorriso on a macbbok 2010 running linux.
I modified some files and rebuild the iso using the /.disk/mkisofs found in the iso.
When I tried to burn the newly created iso on an other mac under macos last updated with balenaetcher, I got a message like “this iso image is not bootable”.
On the old macbook running linux, I got the same message using brasero.
BUT, I succeeded to burn the same file on the same key under macos running unetbootin.
The usb key is bootable and everything is now OK for me.
The question for you is why balenaetcher didn’t recognize the isofile as a bootable image to burn it.