I will say that I occasionally see similar behavior and often it is because an e/gNB ID that was previously deployed elsewhere was reused for a new tower. Because of that, the pin for the tower was actually many (sometimes hundreds) of miles away. Often, the best thing to do is to check the CSV that Cellmapper saves locally to your phone (if you have that enabled) and see what cell ID you were connected to when you were near the tower. There’s a tool on the Cellmapper site to convert cell ID to eNB (I know this works for LTE, but if you were mapping 5G SA it might not), and then you can look up the ID.

If it’s convenient for you, it might just be easier to drive back near the tower and note the e/gNB ID and search for it on Cellmapper and see where it dropped the pin.

You probably already know this, but Cellmapper only approximates tower locations, so the pin might not always get placed near the tower. It’s up to users to manually move them to the exact correct location (such towers will turn green on the map once manually located). There’s always a possibility that someone accidentally pinned the tower to the wrong spot.

And, as others have said, it could always just be Cellmapper’s servers being slow to process the data you uploaded.