Random Hard Crash - stack based buffer overrun in Navmesh.dll

hi all,

During playtesting in the editor, the engine will randomly hard crash with no crash window displayed. After attaching the visual studio debugger, it has landed on the error with an unhandled exception in navmesh.dll, specifically a ‘Stack Cookie Instrumentation Code Detected a Stack Based Buffer Overrun’. I have regenerated project files, i have removed all recent code changes. Here is an image of the location of the failure in .cpp

Any thoughts as to why this is happening?