Whatever the specific causes, there appears to be a link of this issue with channels in a market that have Network IDs of 10, 11, 14, and 15 having channel guide loading failures and those that have a true local NET ID in the range of 512-723 where the guide data loads normally.
Why? ... I don't have a clue. gct did inform me that the usual local NET IDs of 512-723 are actually subsets of Networks 11 and 14, but ... who knows? ...
One common denominator I've found (in my particular case) is that the channels with the problems were all listed as "virtual channels."
When my locals launched, 10 (NBC), 31 (FOX), & 55 (IND) had guide data at 5:35 the morning of launch. Only 14 (PBS), 17 (CW), and 25 (ABC) had "To Be Announced" listed, and all three were listed as a "virtual channel." PBS lost the virtual tag a few days later, and guide information started coming in. CW and ABC continued to be listed as a "virtual channel," which is most likely due to the fact that ABC and CW were imported into my DMA from the Jacksonville, FL DMA, and were the same signal remapped (from the Jacksonville, FL spot-beam). When 44 (CBS) was added a couple of months later, it had guide data (and was NOT
a "virtual channel") from the start... heck, it had guide data even before it started.
When the CW and ABC feeds were replaced earlier this year with LOCAL SD MPEG4 feeds, they too had guide data from the start. HOWEVER, with the replacement of our PBS with another neighboring PBS (identical state-wide channel) on a different spot-beam, I am once again seeing the "To Be Announced" bug again... and guess what, it's a "virtual channel."
It COULD all be a coincidence in my market... and the two channels in Rapid City, SD might not be "virtual channels," but it is something I've noticed. As veryoldschool has stated, it appears to be a "receiver/authorization type problem"... but in my market, it appears that somebody is forgetting to throw the switch (so to speak) on virtual channels...