This situation can be caused by 2 factors.
Your IP is excluded from analytics
The Video is watched less than 0.1% of the total video length
Your IP is excluded from analytics
If the option "Disable my IP from analytics" is activated, then a view from your IP address will not be counted.
You can find this option by navigating to your App Settings >> Global Options tab:
Video is watched less than 0.1% of the total video length
When someone watches a video less than 0.1% of the total video length, it is not enough to be considered as a "play".
For a play to being considered as a legitimate play, the video needs to be watched at least 0.1%.