Hi Em, could be either a late o or anovulatory cycle. You asked how common anovulatory cycles were - i'm not sure on percentages but i personally have had 1 that i definately know of in the last 12 months. I guess it just happens as i was given no reasonable explanation. During that cycle i didnt get ewcm either.
But it aint over till the fat lady sings so i would just keep bding and monitoring cm and cervical position. When you o is should be high and soft and when you are not fertile low and firm.
All the best.