Most Dominicans I've met don't deny Blackness. They just don't prioritize race over nationality. To them being Dominican is more important than being Black. To Black Americans that comes off as weird, but we gotta stop bashing Black people that are from places outside of America for not seeing things the exact same way we see it. That said, non-American Blacks do have to understand that shit works different in this country. They try to come here and behave like things are the same as back home for them, and they get a rude awakening.
I've met a lot of Ethiopians, Kenyans, and Somali, and I've never heard any of them deny Blackness. I do see them object pretty strongly to being associated with Black Americans though.