I think this is an obscure bug, searching reward travel tonight I was trying for CLE-GCM, it would present the following error when searching for departing Thursday August 28th (and also Friday, August 29) , returning Sunday August 31.

Continental or its partners offers service between Grand Cayman Island, Cayman Islands (GCM) and Cleveland, OH (CLE) on Sundays, Mondays, Thursdays, Fridays, Saturdays.

Even searching non-reward travel presented the same error message for selecting any departure on a Thursday or Friday.

The message should be changed to not include Thursdays or Fridays or the schedule changed to include them...