still in 4.19.2–only 3 areas where it does it, and no, they aren’t sloped areas, just areas not on level areas, created via sculpting, and later refined with flatten tool.
I hope that helps narrow down collison issues in ue4 4.19.2…its unnerving 
Stops dev as I can’t risk it anymore without a firm fix.
Lumberyard to the rescue,and they have 32bit terrain support.
NOt down for the count w/ue4, but I must work around it, for now.