Comment # 11 on bug 1191480 from Stephan Hemeier

Same here, with --ignore-keyring I got my key to mok.

Before it was always:
# mokutil --import /etc/uefi/certs/F2B7BCC9.crt
> Already in kernel trusted keyring. Skip /etc/uefi/certs/F2B7BCC9.crt

And not shown in mokutil......

Now after restart, I could enroll the key and all is working.

PS:
I branch the kernel:stable:backport in my Repo so I have another key.