As 1 deg = 60', 1.7 x 1.2 deg is actually equal to 102' x 60'. If the size of the sensor is w x h and the focal length of the scope is f, then the FOV is given by

FOV = 2*atan(w/2/f) [horizontal] ; 2*atan(h/2/f) [vertical]

And by entering the figures given by @gbeaton we get a FOV of 1.698 x 1.273 deg, which is in line with values reported by Ekos and by online calculators. Now, this value may be a little bit different compared to solved images due to the fact that actual focal length may be slightly different from nominal focal length, see also @kbahey post.

Some questions for @gbeaton:

1. Are you using real hardware or simulators in your test?
2. Did you tried Online solver mode? Do you get the same results (failure)?
3. If you use Load & Slew with a real image instead of Capture & Solve, does anything change?
4. If you manually upload your captured images to astrometry.net, do you get a solution?

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