I have this written up for when I see a wheresmypokestop question.
I know the prompt tells you that you are submitting a “Pokestop” but you are actually submitting a Wayspot to the database. The Wayspot can only become a Pokestop or gym if it is alone in a level 17 S2 cell. The S2 cell use has not been officially confirmed as far as I am aware, but staff has acknowledged there is an additional step after acceptance. This is a good article about S2 cells and how they have been observed to be used in PoGo: https://pokemongohub.net/post/article/comprehensive-guide-s2-cells-pokemon-go/
Eligible Wayspots are added to Pokemon Go in a sync that happens once a day normally. If it has not been more than 48 hours since it was accepted, it could just be that it has not synced in yet, even if you see the “Wayspot used in other games” message on the nearby check in the nomination map screen.
Wayspots that are not eligible to be Pokestops or gyms still have the potential to be used as Power Spots. It appears that there is a 22m distance requirement from any Pokestop or gym for it to be used this way, and it seems there is a limit of two active Power Spots per L14 S2 cell, the same size used to determine gyms. The schedule for syncing in new Power Spots is not on a daily basis. The last few syncs have been on the 4th of the month.
If you would like to start a topic with the title and location, someone here with access to external resources may be able to confirm if there is indeed an issue with the S2 cells. But since the sale to Scopely has affected these NianticSpatial maps being updated, it may be more difficult. The gps coordinates where you pinned the Wayspot will be after the second photo in the email you received when you submitted the nomination, but the pin may have been moved in voting.
There are other reasons a Wayspot may not be used in Pokemon Go, but this is the most common.