Make sure the maps are .bsp files (not .bsp.bz2) in your momentum/maps/ directory.
Please don't start multiple threads just because you haven't received a response on this one. It's just going to clog up the forums, so I've deleted the newer one.
The best way to get help with this is in our Discord (https://discord.gg/n4v52uv) as we'll have less of a back-and-forth like this.