I will set a Know Issue because this is a non supported feature. Actually, the modifier works from first to last point, and the cyclic flag is only at draw time (not real geometry), so the section that closes the stroke is not subdivided because it doesn't exist as geometry.. To add this feature, I would have to implement the same algorithm used when you select first and last point and press ' F`. In this case, the algoritm adds points at the same distance of the average distance in the stroke.

I add this feature to my ToDo list.