I've been having the same problem for the last few days on about half of the Boston locals. I called dish tech support yesterday and the guy on the other end said that he had fielded four straight calls in a row on the same problem but that there was no known issue yet in the system.
This morning everything seemed to have been fixed but as of 7pm tonight, the problem has come back again. All of the major networks have data, but the remainder of the local channels show "no info available" after the current hour.
If anyone has any info on this that would be great; else I'm going to call back Dish on Monday.