I've mentioned this bug before. The radar display often loses all the returns for the last frame. I suspect this is due to the smoothing algorithm (or animation).
Frankly: I'd rather you just put the "return" point as delivered (intensity at that location) from the source and not attempt the smoothing/animation.
And PUUUULEEEAZE! Turn off the default sound and lightning.
What is showing:
Frame "just before"
What Env Canada is showing at same time as image at top.