The hyena that made its home in a wolf pack

[Svartalf]

but the offspring is sterile, is it not?

[mistermack]

but the offspring is sterile, is it not?

No, it's not, apparently. They must be very close genetically, although they are closer still to grey wolves and coyotes.
This is from the wiki page on the African Golden Wolf, the most widespread one :

In 2015, a series of analyses on the species' mitochondrial DNA and nuclear genome demonstrated that it was in fact distinct from both the golden jackal and the grey wolf, and more closely related to grey wolves and coyotes.[5][6] It is nonetheless still close enough to the golden jackal to produce hybrid offspring, as indicated through genetic tests on jackals in Israel[5]

If the jackals in Israel carry their genes, I think the offspring must be fertile.
This is their range. I found it very surprising :