Feel like the level of "African" with the Black parent determines how ambiguous the kids look.
A person that's 85%+ African mixes with any race of, it will produce Blackish looking kids (Lenny Kravitz, Obama etc). If breh is like 70% Black or some shyt....you can come up with all kinds looks (Rashida Jones).
Sometimes white + Black will make the kids look Arab (Kapernick) and other times look Puerto Rican or some shyt.
White + anything else usually just looks "off white".