Is it possible for the IPAD to show image photocenters in PIX4D Capture for a flight mission but have no actual images written to the SD card?
It may be possible. The reason I say that is that I recently noticed, during Pix4Dmapper (desktop) processing after a 20-minute flight, that one or two images appeared to be missing from the displayed Cameras. Since the forward and side overlaps were planned for 83% and 81%, the images that appear to be missing were not a big concern for this job over fallow farmland. I don’t think the card’s write speed is the root cause. The root cause may be insufficient time for the camera to finish making auto-adjustments from 200 feet on a sunny day over bright cut grass.
That said, having zero images recorded on the microSD card appears to be a different problem. The physical design of the card makes it very difficult to insert incorrectly. There could have been contamination on the card’s contacts. The card could be defective. I have heard complaints that the card holders/connectors have a limited number of duty cycles (insert, eject, … ) before failure. Then there’s the possibility that the format of the card was not compatible with your drone/UAV, which would be the first thing that I would check, since I’ve experienced that problem.