Map renamed in Cartography Table reverts to default name after exiting realm.

Hello When I go to name a map in the cartography table I put it in one of the first slots to the left and then enter my text, I then take the map and put it in my inventory and the map has actually been renamed, However when I leave the world and come back again the map name reverts back to the previous default. My game version is 1.18.31 i also own Minecraft from the windows store.