Comment # 14 on bug 1171180 from Michal Suchanek

Why does it not work?

The code seems to match zImage:

default_kernel_images() {
    local regex kernel_image kernel_version version_version initrd_image
    local qf='%{NAME}-%{VERSION}-%{RELEASE}\n'

    case "${DRACUT_ARCH:-$(uname -m)}" in
        s390|s390x)
            regex='image'
            ;;
        ppc|ppc64)
            regex='vmlinux'
            ;;
        i?86|x86_64)
            regex='vmlinuz'
            ;;
        arm*)
            regex='[uz]Image'
            ;;
        aarch64|riscv64)
            regex='Image'
            ;;
        *)  regex='vmlinu.'
            ;;
    esac