I am unsure, through I suspect it is an 811 bug. I believe I saw other posts in this forum discussing the issue before I was inflicted with it. I was planning to call Dish when I get some time. I'll post a report when I do.
I am a Milwaukee area user with an 811, and had the exact same experience. The 811 scanned & held the local CBS channel after the 269 update, until a few days ago when it disappeared, and keeps disappearing.
I am still waiting for the update as well. Still not installed as of 8:00 am this morning.
I installed & activated my 811 receiver 2 days before the 269 software was released, so I may be one of the last on the list.