Based on your camera setup it might happen that the 'Sync-LED' of the camera indicats for a connected IRIG-B time signal (green Sync LED is ON permanently) but your on screen display shows 'No IRIG time signal detected'.
One feasible solution in that case is to check on the quality of the IRIG-B time signal connected to your camera. Based on your setup it might happen that
- the polarity of your IRIG time signal is reversed
- the IRIG time signal is noisy
- the data of the IRIG time signal is not valide