zzmoenorman: after I saved the game I played in CC event
1) At that moment, you should have been asked whether to continue the RG game.
(assuming you played on PC)
2) When you played in the CC event, you forfeited the RG game.
zzmoenorman: When I attempted to start the game it notified me I could not play..
That was because you had already played (and forfeited) the RG game.
Unrelated: After an error code, anything is possible...