It seems that dominant layer info in landscape collision components is lost when changing the collision mip level. For a repro open the attached project and run the Landscape map. You should see the sphere falling through the hole in the middle. If you stop the simulation, change the collision mip level to 1 and re-run you will see the sphere landing on the landscape. Could you have a look at it?
I was able to reproduce this on my end and have entered a bug report, UE-15833 to be assessed by the development staff.
Hi Luis, Thanks for your report. This was fixed for Unreal Engine 4.8, and the source code change can be found here:
This fix should also be in any of the 4.8 preview versions if you want to try.
Thanks . Tried it locally and works perfectly fine.