By default UE4 uses a maximum of 2048 navigation nodes to search when you request Find Path to Location or Find Path to Actor. This can be problematic when you want to find path to a larger distance. You can modify the limitation by opening DefaultEngine.ini and adding the below section.

[/Script/NavigationSystem.RecastNavMesh]
DefaultMaxSearchNodes=4096 ;2048 is the default. Change it to whatever value that works for you.