Problem with GetRandomPointInNavigableRadius

Hi.
I have a map in my project, and the floor in it consist of chunks.
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When i try to spawn AI using GetRandomPointInNavigableRadius or GetRandomReachablePoint, point those nodes return are out of NavMesh. For example, on this screen i got correct points for 2 AIs, but one AI spawned outside the NavMesh.
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It happens only on the map, where the floor consists of chunks. If the floor is one big mesh, then everything works fine, even near the border. The problem disappeared when i put chunks one on top of another more than half of their size. But this solution is not an option.
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Could someone help me to solve this please? Maybe i forgot to enable some option, or it is a bug in ue4…

Maybe shrink up the mesh to just inside the walls? Also you could maybe use a object to spawn within a certain radius of instead of using the mesh? Haven’t done this yet but those are what I would try.