Hi Cameron,
currently we are using Version 10.9.3. As video source i use a Terranex-Converter and a SDI Crossbar/Router to multiply the video feeds, all synced by the Terranex Ref-Out.
The dropped frames do not occur on a specific channel and in no regular manner.
Using the test application, when you go slowly up with the CPU utilization. At a certain point the devices start to drop, and when CPU utilization is decreasing the devices seem to recover.
Our "real" application is by far more complex than this sample but as long as the dropped frames occur in this simple application its hard to make progress.
Concerning your advices:
(1) I just forgot to check the pointer in the sample...

(2) That was my first thought too, but i check the time spend in
IDeckLinkVideoInputFrame::VideoInputFrameArrived and it was always far below 1ms.
I even provoked a delay of 10ms... no frame was dropped.
Regards
Steffen