Although the prompt tells you that you are submitting a Pokestop, you are actually submitting a Wayspot. In order to go live in Pokemon Go, a Wayspot has to be alone in an L17 S2 cell. I will link a good article about that:
I want to be clear that pinning away from the thing you are nominating so that it is alone in the cell is abuse, but you can certainly use this knowledge to help you decide where to look. If you want to leave the location here, someone can check to see if this is the case for this nomination.