Just a couple of comments. The image was captured with Nebulosity and the FITS headers that were inserted are formatted very differently than headers inserted by SGP. Not saying they are wrong, just different. SGP is not able to get the hint from the headers that PlateSolve2 needs to be successful but even when an accurate hint is given, PS2 still fails to solve.
I was successful in getting a solve from Astromentry.net. My stand-alone copy of PinPoint also fails to solve even with an accurate hint. PP reports this image contains 84,000+ stars and PS2 shows the image size is 222' x 148' and Astrometry.net shows the plate scale is 3.33 arc seconds / pixel.
I suspect this image is simply overwhelming both PS2 and PP because it captures a much bigger field than either of those programs were designed to process.
Personally, I have found PS2 to be very reliable with my SGP images (KAF-8300) but my images have 100X less area than yours!
It would be interesting to get some feed back from SGP users that have STL-11000 cameras.