Unity 5+ has a major bug with the default Character Controller that causes it to randomly stop detecting random collisions. Sometimes it can be buildings or otherwise it could be the terrain itself. It happens on non LOD buildings as well so I do not believe its an LOD script issue.
|Open||Natfoth||T17 Collision Detection is messed up because of the Character Controller|
|Resolved||justin||T33 Can't Go Up Stairs|
|Duplicate||None||T168 Water animations|
|Wontfix||Natfoth||T255 Object Collision Jump Glitch|
|Open||None||T1082 Wigglestitch's building has a odd and sticky window|
|Open||justin||T1040 Being between bundles of hay and small building will get you stuck|
There was an attempt by Tekner a while back to switch the player controller to a rigid body system, due to not being able to get trigger enter/exit events. I have some code that I don't think he used that gives you an interface very similar to the character controller, but with the rigid body