Multi-boot Menu: "Now You See It; now You Don't"

This has been going on now for a year. A Tumbleweed update with a new kernel wipes out the other OS listings in the boot menu - Win 10, Linux Mint. But not always. Sometimes the boot menu is intact after a kernel update.

When the boot menu is erased (of the other OS’s) I reboot into Tumbleweed and rerun YAST Bootloader.

Can someone explain this phenomenon?

You haven’t explained what you are doing.

My boot menu is intact after Tumbleweed updates.

I’m running the updater when it displays updates are available.
I’ve gotten used to running YAST bootloader after every update that installs a new kernel. But sometimes the multi-boot options are preserved after a kernel update.There is a text file in /boot/grub2 that mentions how a kernel update can wipe out the boot menu.

As far as I know, after a kernel update the program “/sbin/update-bootloader” is run. And that should run

grub2-mkconfig -o /boot/grub2/grub.cfg

That completely regenerates the boot menu. It should be finding other linux systems by running “os-prober”.

If some of your other systems are encrypted, then “os-prober” may not find them.

If you want to manually add entries to the menu, it’s best to do that with “/etc/grub.d/40_custom”

None of my other OS’s are encrypted. Evidently, on both of my systems running Tumbleweed, the automatic running of grub2mkconfig is not happening after each kernel update, just sometimes. I know how to deal with this, but it is puzzling why this behavior is inconsistent.

Using the updater? Don’t. As per documentation,

zypper dup

is the only way for TW,