Weird Black Dotes and Light Bleeding

After Several times testing on difrent LightBuilds, it occured to have such an issue, :

A- Black Dotes
B- Light Bleeding

LightBleeding is kinda known, but those “Black Dotes” are so interesting for me that I decided to post an qeustion if someone knows an solution or explanation to this problem. If you “fly/move” into the scene it takes couple seconds before the scene and the dotes get whiter.
LightMap Res =2048( UE4 Automatic Generated LightMap)
Rest Settings On Screenshot.

Can you have an to much LightMap Resolution ??
I have watched that Light Map resolution can be 6*64 = 448[px] or 512 + 64 =576[px] , is this valid ?

Thank You.