Hi there,
When I encounter that kind of problem, I do the followings:
1- create a dome light ( intensity:1 ) and attach your hdr map to its texture parameter.
2- In the dome light parameter section, you'll see a " spherical full dome )... Check this
I think your problem is occured because you tell your hdr map sphrefy rhe hemispherical sky, so ground level's color determined by environment map ( pressing by "8" )
I hope this could be helpful,
Greetings.
