I found the post where it appears another person is having the same issue: https://answers.unrealengine.com/questions/54986/collision-of-a-sliding-object-on-landscape-is-poor.html
An Epic employee mentions it was not fixed but that was over a year ago.
Edit: This thread seems to indicate that that issue was fixed https://forums.unrealengine.com/showthread.php?9215-Videos-Rama-s-Victory-Landscape-Collision-Plugin&p=72991&viewfull=1#post72991