I get similar issue, after 4.17 first launch and, please try to move your NavMeshBoundsVolume and cause to recalculate teleportation zone! You can see this zone select NavMeshBoundsVolume activate viewport (i mean get in viewport, you can hold right click and change position of view) pressing pand you have to see green area !
or go to project settings>engine>navigationmesh>generation>cell size and cell height will effect your possible teleportation zone.
I hope it will help you guys…
Cheers