Club Log has extensive lists of exceptions for special callsigns. For example, calls like K5D or K7K are known. These callsigns are mapped correctly provided the QSO dates are within a known window of activity.
Some logging software does not know that K5D (for example) is not just USA, but actually Desecheo for some very specific dates. Understandably, DXers are tempted to log K5D/KP5 (for example) to force their logger to recognise these rare ones properly. However, when such forced callsigns are uploaded to Club Log, they are rejected. The reason is that no such callsign is known to have been active from that rare DXCC, and the Club Log whitelists will block it.
The answer to this dilemma is to log K5D (with no embellishments). Try to get your logging software to manually override the DXCC entity, if it is not getting it right. This problem is gradually going away as more logging products use the Club Log definitions in the first place.