I rescanned the Slingbox channels at setup.slingbox.com -- the issue remains, regardless of whether the playback is in the installed ActiveX control or the standalone app.
What additional information are you looking for regarding my cable service? As for my configuration, I have a coax drop connected directly to the Slingbox (no cable box), so I'm using the internal QAM tuner.
Comcast here provides a various mix of clear QAM channels (1080i, 720p, 720x480i, and some downconverted ones, like the problematic 528x480i). You can see the lineup here:
When a 528x480i channel is tuned, there is no video/audio output, and the Statistics window shows a height/width of 640x480. If I manually set the SlingStream encoding to 320x240, the problematic channels do play -- however, that's not a solution...
I've tried tuning some of the other SD channels. 720x480i works, but 704x480i does not. In addition, tuning a 1080i channel after having a 720x480i channel on results in "Weak or no video signal detected". To recover, I need to tune to a 720p program, then the 1080i channels work.
As far as the AFD issue, that's a little more complex to describe. It's usually a problem during Fox sports broadcasts on the Boston affiliate -- which are now in widescreen. when the local affiliate cuts in its own commercials, it drops to "Weak or no video signal detected". The picture recovers a few seconds after the national feed returns. I'm guessing that the local station is not handling AFD properly, which is confusing the Slingbox. The NBC affiliate (also AFD) does not exhibit any issues.
Let me know what other information I can provide...
I'm seeing this same problem on a new Slingbox Pro-HD I just got today. It doesn't stream 540x480 clear QAM channels using the built-in tuner unless you turn the streaming resolution on the slingplayer down to 320x240 or under. I'm in the Denver area using Comcast. Any solution to be able to use it at full res?
Contrary to earlier replies, it is not "your problem" . I was contacted by Sling offline to pursue the issue. I provided access to my Sling remotely so they could further investigate it. AFAIK, they did examine the various QAM channels on my cable connection -- however, I haven't heard back from them regarding a solution yet.
Based on this, in conjunction with some other QAM anomalies (cropping of 720p feeds, AFD issues, etc.), which I believe appeared in a recent firmware update, my guess is that we won't see a fix until there's an update from Sling.
As I've noted, I also have an HD DirecTV DVR connected to the component inputs, where none of the resolutions have any issues. Combined with the fact that I really only use the cable input to view a few local HD channels, it isn't dramatically impeding me. However, if you're a regular viewer of one of these downconverted QAM channels, I could imagine the frustration.
Hopefully, we'll see an update soon...