After some more experimentation to figure out what’s wrong, I observed that my NavMesh would disappear upon play each time.
I then started deleting actors in the scene one by one to determine what was responsible for making the NavMesh disappear.
I then ended up again with basically no actors in my level, other than the plane, the NavMeshBoundsVolume, and some lighting, while the NavMesh would still weirdly enough disappear each time on play.
Ultimately, I simply ended up creating an empty level and copy pasting over every actor from the previous level where the NavMesh disappeared on play, and weirdly enough again, the NavMesh now doesn’t disappear in this new level, and everything works as intended.