To Reproduce:

1. Open scene ‘1_NotGeneratedOnSomePlatforms’, observe that all the boxes except the larger one in the corner are absolutely identical.
2. Select all the boxes in ‘GameObject' go to Navigation/Bake and Bake.
3. Observe that NavMesh is generated on some of the boxes even though they’re identical, while not on other ones.
4. Change Min Region to 1: NavMesh is generated on all boxes
5. Notice that when Min Region is 7, NavMesh is no longer generated on the larger box, but it’s still generated on the two small ones.