Jason,
Being an owner of the C500 + AJA Ki Pro Quad combination I have too been puzzled.
Recently testing 2K at 59.94fps I have gotten similar results.
The recorder appears to record the data fine upon playback internally on the AJA device, yet once viewed on a computer the footage reveals only a black screen, yet the duration of my clips has remained.
This is not a codec issue as I’ve successfully viewed/created with 4K AJA recordings below 29.97
Has AJA gave you an answer?
Purchasing the recorder was greatly revolved around shooting higher 2k frame rates that appeared possible according to the companies text.
Ahh the frustrations of new technology.
-FAWN