I never had any luck using my Kitchenaid to churn butter, no matter the time of year or where the cow was in her lactation. I've been using my food processor and that makes the cream turn very quickly, most of the time.
However, last year after she had impacted her rumen on rich alfalfa hay, it took 15 minutes for the cream to turn, as opposed to about 3-5 minutes all the rest of that year. So maybe your cow's bloat did have something to do with it.
I personally don't care for cultured butter.