Where I would be able to find this?
Movement Component is part of 3rd/1st Person Character
Or part of anything you add this component to
To anyone else ■■■■■■ off unable to fix this, idk wtf they meant by wrong movement component, but in my case I had messed with cell size settings and it permanently messed up my level / project. I had to make a new project and migrate all assets, then copy paste outliner objects into the new project. Then I put in a nav mesh and it all worked fine.
After losing an entire day to this glitch, my research concluded with there are multiple bugs that can cause this with multiple solutions and if you too have this, you have to try one after another until you get lucky. Anyway, making a whole new project and importing everything resolved the issue, my old project has permanently messed up nav meshes after changing settings and nothing I did could undo whatever bug happened to them.