Woodland Explorer map pre 1.17 does not lead to 1.18 Mansion

Looked at a Woodland Explorer map pre 1.18 but never went to it and generated the chunks. I finally got there, and it lead to the middle of an ocean and no mansion. The river markings do not line up at all, everything is ocean. Before traveling here I bought a second map and looked at it, but it looked identical to the one I got earlier. /locate tells me the nearest mansion is 10000 blocks away.

I'm playing on a Realm.