I don't know how often ESPN will check with your provider (Comcast) for up-to-date information on what channels you currently have once you've logged in once. But if the last time they checked was before the Comcast/ACCN deal, it's possible that they still think your service doesn't include ACCN. If you log back in, I expect that will force an update of your cable information. (I hope that Comcast and ESPN now agree that most Comcast customers have access to ACCN, but I don't have Comcast so couldn't say that for sure.)

I updated my provider like 4 times this past weekend as I switched from YouTube TV to Hulu then to Fubo TV and then back to YouTube TV again!