It should not be related. It is caused by quite stupid behavior of yast2-bootloader which in some cases overwrite branding variables written by grub2-branding packages. We already have this bug in SLE12 and solution is if your installation images contain grub2-branding to move it out and force grub2-branding to be installed from rpm, otherwise yast2-bootloader overwrite branding specific options in grub configuration.