Why US-British coordination fractured after Roosevelt

Was there a breakdown in communication between the United States and Britain after the Second World War?

Yes, driven in part by an internal US coordination breakdown after Roosevelt's highly personalized wartime system lost its central manager.

Some American offices continued talking to Britain while others pursued policy without coordinating internally or with their ally. Much of the breakdown followed Roosevelt's death because the wartime system relied on his long tenure, informal influence, and ability to control competing personalities. Truman could not immediately reproduce that combination of personal and formal authority. The resulting institutional fragmentation helps explain contradictory postwar decisions that affected Britain and the wider Western security system.