I went on search for an Ocean Monument, and when I started filling the map and to get real close, there was no Ocean Monument.
According to the Minecraft Wiki, Ocean Monuments only generate, well, on the Ocean Biome, and as you can see... I'm in a forest, where the Map is pointing, exactly where I am.
I dug down to see if the Monument somehow generated underground, and no, there was nothing but stone. It's also not above.
I bought the map to a villager in the 1.11.2 version and started filling it in 1.12, I don't know if that's the cause.
I tried restarting the world, but it did nothing.