Completed 5 today no credit. Did all pre/post steps.
Continued and completed 6. Got credit for 6.
Restarted 5. There was a purple star next to Blue Oasis in Silverwastes: "Replay: Caithe's Reconnaissance Squad" either was not there before or I missed it. Enter the purple instance and got email and credit immediately after the last step "get on the chopper."