I lived through many, many lingering impairments and outages over the 18yrs I spent on the job. In the early days there were lots of people watching lots of live monitors that could catch minute problems and either switch to a backup or get people on it immediately. Now most everything is automated with very few eyeballs watching monitors and certain intermittent problems can go on for hours if the automation doesn't catch it to inform an operator.
However, the broadcast chain is very complicated and there are lots of problems that don't show themselves very easy and these get handed off to higher tier experts to diagnose. Often this takes time because the problem can be buried deep like a glitch in the compression system that nobody has ever seen before, or something not obvious in the IP stream or something in the RF chain that appears normal but is not. You can also have problems where the only solution would affect many more channels and they are hesitant to compound the outage.
When I hired in, every second of outage was an eternity and when an intercom went off announcing a problem we grabbed our tool kits and sprinted to the affected equipment area like it was the Olympics. Today, not so much. The broadcast chain has also gotten much more complicated over the years with everything being an IP stream and a problem in Southern California might require a team somewhere else in the country to help diagnose and reroute traffic, etc.
Nobody posting in this thread was at a broadcast center as far as I know, so we will never know the exact cause or fix for this specific problem. Based on the scope and duration of the problem I will go out on a limb on the DTV technical side and say people were probably on it very early and it was a whopper to fix.