busybox or busybox-static package is needed for update initramfs must run after kernel updates. The busybox-static package is missing on the Tinkerboard and Odroid C2 image (may be others).
I filed a bug report here:
[busybox or busybox-static is needed for update initramfs · Issue #1124 · armbian/build · GitHub](https://github.com/armbian/build/issues/1124#issuecomment-427852788)
Apparently it was not the right place. It got closed immedeatly:
> The issue is closed for two reasons: it contains no valuable info and it's in the wrong place.
I still consider this to be an important bug, so I leave a trace here.