Sure - if this is the same one, it was due to having a Corona Sky Tag on the Sky object along with the HDRI material. Only the HDRI material should be used, as a Sky object can only have one "active" material on it. With both applied, while the HDRI showed up in the realtime viewport in C4D, only the CoronaSky tag was being used in the render. Deleting the Sky tag and leaving just the HDRI got the required result (also, changing to a Corona Light Material rather than a Corona Material was done too).
