Your submission is in the 20 meter radius of a different POI (not all POIs are in Pokemon Go, but still count for the distance-rule). If your submission isnt in ingress, it got sorted out after the approval by the Nia system. You can submit it again with a different location (only if you got a specific area, for example on a playground, do not fake the location because of this rule!)
Your submission is in a full lvl 17 s2 cell (only for Pokemon Go)
Your submission is newly accepted and you have to wait a bit until it is getting synced to Pokemon Go (up to 34 hours)
A syncing error is blocking newly submitted POIs to get into the games, so it can take a little longer than 34 hours until they will appear in ING/PGO. Mostly, only one game got syncing errors, so you could check the other games to check for your POI.
The location of the POI is in a geoblocked area, meaning that POIs inside this area might not spawn in a specific Niantic game. Also it is possible, that some POIs might not qualify for a specific status ingame.
Comments
Q: My accepted submission is not ingame. Why?
A: There are five posibilities:
Did you check it on Intel map?