Why are models falling through in some parts of my landscape?

I am using 4.7.2 version of UE4. Early I converted this project from 4.7.1 to 4.7.2 UE4 version.
Why are models falling through in some parts of my landscape?
For example:
I created some mountain-style landscape and add some foliage to it. Then I add First Person Character and play by it. In some parts of landscape(mostly in skew surface) this FPC are falling through landscape surface.
What is the problem?

Also when I am playing FPC collides with invisible obstacles which have very big height.

Hi CrazySiberianScientist,

While I was unable to reproduce this error on my end, we have had a number of users experience this collision bug. I went ahead and put in a bug report, UE-11447 to be assessed by the development staff. Can you try the workaround suggested below and see if that fixes your error:

We just fixed a bug in 4.7 where collision for landscape components containing XY offset data (generated by the Retopologize tool) was broken. The fix will be in 4.7.3 which should be out next week. If you’re using source code you can apply the fix directly before then if you’d like:

https://github.com/EpicGames/UnrealEngine/commit/cbaaca1e870bce1aae32ba5d0c7dcd48c7b6aea2

Cheers

Hey there,

I’m having the same exact problem. However this only occurs on landscape i haven’t touched in a little while. My map is quite huge so it’s normal some parts are done that i don’t touch because it’s done. But recently i tried something out in an area that was done but randomly started falling through the landscape with my FirstpersonCharacter and my Vehicle. Also on a side note my meshes, as soon as i turn on Physics it just falls through the ground on every spot on the map. However everything is set at BlockAll. Also i haven’t used Repotologize as said in the other posts. Is there any idea why my meshes would fall through as soon i turn on Physics? I’ve asked 3 people with months of expierence on UE4 But they didn’t see any problem either. Is this because of the same bug?

Kind regards