Trying to finish CoP mission 4-3 The Secrets of Worship solo.
I went to the Sacrarium, and found the Sealion and Coral Crest keys. Once these keys were obtained I went to Quelveuiat in the Tavnazian Safehold, and immediately undertook and finished the quest; A Hard Day's Knight. After completing this mission I traded the Sealion Crest Key and the Coral Crest Key in hopes of receiving the Temple Knight key. However, Quelveuiat did not give me the key.
Since I have traded these keys I have also tried to farm them again, in order to try and trade them again, however the keys will not drop now.