This is an issue I ran in years ago when having multiple instances of Mageia running for testing. I noticed then that as soon as there are a number of kernels, grub2 just does not have the latest ones as defaults in the grub2 menu when booting. And as this is a UEFI capable box, there is a /boot/EFI partition.
Now I have a similar issue:
My testing laptop has Mageia 9 on /dev/sda2 using grub2. I installed OM Cooker a few weeks ago on separate partitions (/dev/sda5). But I cann’t remember whether I had a choice of boot device during installation or it picked the existing situation. Anyway, I had a working grub2 menu with entries for Mageia and OM (plus advnced for both, and one for UEFI settings).
In the mean time system updates came along and at a certain point I noticed that the default for OM in grub2 remained on the first kernel version (6.9 at that time). in that time there had been another 2 or 3 kernels installed. I didn’t dare to manually change the grub config , it being rather complex. I ran update-grub2 and that nicely listed the kernels it found (including the Mageia), but when I booted, nothing had changed.
I deleted the older kernels in dnfdragora, reran update-grub2, butt that had no effect on the grub2 menu at boot, it still listed the old removed kernels. Remembering the old issues, I booted into Mageia and ther forced the boot loader to OM kernel 6.13 now. That works well, until next kernel?? I don’t know how to control grub2 in another way in OM.
I gave up on Grub dual booting when UEFI systems came into effect. Now, I remove all drives but the one I am installing to. Once complete reconnect all the drives. When booting, as it passes the UEFI, I just hit F8 to get the boot menu and select which system I want. It’s just simpler and I never have to worry about one system borking the others.
I don’t know if anyone else does this, but it works for me.
I also install grub-customizer and tell grub not to look for other OS’es
I no longer dual boot, but I used to run update-grub && grub-install
or grub2-mkconfig && grub-install
to get the correct kernels showing, can’t exactly remember. There is a way to get os-prober involved in that to always pull in the correct kernel options for your other OS’s, but I can’t remember how to do that either. I do remember when I first switched to linux and was constantly hopping around that my Mint grub couldn’t see my Manjaro install no matter what I tried, but Manjaro’s grub could see Mint but not boot into it. The only solution I found was to write my own custom grub entry and update it manually every time I updated.
Check with lsblk to see if the /boot/efi partition is as expected or if installing OM created another. It could be update-grub2 is updating one partition but you are booting from another.
You could also use efibootmgr to see if it lists 2 different boot entries one for mageia and another for OM. This info would be usefull before digging into grub settings.
After all these years, one would think that grub would be awesome, but no.
Tx, running grub2-mkconfig got me a decent grub2 menu at boot with all entries I expect, all the old ones have been removed. Now up to the next kernel update, I wonder.
Glad you got it all sorted out.