Were power struggles and segregation a problem amongst black South Africans during the postapartheid period?

There were indeed divisions and power struggles among black South Africans during the apartheid era. The main struggle was between the African National Congress, the principal political and military movement struggling against the system of forced segregation imposed on the country’s blacks by the minority white government, and the nationalist movement of the Zulu tribe called the Inkatha Freedom Party led by Chief Gatsha (Mangosuthu) Buthelezi. Buthelezi had been aligned with the ANC but eventually broke from it due to the tactics required to remove apartheid and calculations of what was in the best interest of the Zulu Nation, the largest tribe in South Africa. Buthelezi enjoyed a great deal of legitimacy among the Zulu, and his opposition during the 1980s to the Western-backed anti-apartheid economic sanctions and boycott movement was a major source of irritation between him and the leadership of the ANC.
Buthelezi believed that the level of economic development that the KwaZulu territories enjoyed was a symbol of the advancements blacks could make even under apartheid and that sanctions against South Africa by Europe and North America would prove damaging to all South Africans, not just the small minority of whites in power. His positions on the anti-apartheid movement and his decision to champion the causes of the KwaZulu Nation above all others remained a point of contention with the ANC throughout the 1980s and made him highly unpopular among anti-apartheid activists in the United States.