SD channels, many now missing showing error code 225

I just noticed starting this morning many SD channels won't show program picture or sound when trying to tune to those channels. The HD corresponding channels show programming OK. The Channel Guide still shows these SD channels as existing with programming. I have the Digital Starter TV program plan. These SD channels won't show on both my DTAs and one HD DVR (all Xfinity equipment). Restarting and refreshing devices still results in the same missing SD channels. Xfinity website inquiry shows no outages in my area. Has Xfinity decided to eliminate these SD channels (DISC, HALLMARK, ROOT, ESPN, NBCSN, FOOD, HIST, TLC, NIK, DIS, TOON, A&E, TNT, TBS, BET, USA, SYFY, COM, VH1, MTV1, E!, BRAVO, AMC, HGTV, etc, etc)? There was no notice given that these SD channels were being discontinued.