Yes, 3 navbounds (1 is a dummy in P-level, 2 in each sub level) and 1 recastnavmesh in P-level. You may also try delete your recastnavmesh and create a new one. Also be sure your pool size are enough. Nav-mesh should stream when start play. Be sure you have rebuild nav-mesh with Navigation Build Paths. Use P key to see nav-mesh cover your area.