Thanks a lot. This package was missing indeed. After the install, "armbian-release" was created, and armbian-config now shows a list of kernels properly.
I have a feeling that if I install this package before the initial kernel upgrade from 5.xx, there would be no need to update the "uInitrd" manually, as I did in the first step. Will check later.
Yes. This problem magically disappeared after the "Update all packages" command and reboot, now it's fine. Maybe the locales were regenerated during the process.
