Weird leaking effect happening on my map for no reason.

So, I was detailing sharkbay, i added roofs and stuff to many buildings so there are not flat anymore and I added some details as well, i thought this area close to the spawn needs to have a fence overlooking outside to give it a feel of depth. I run the game but i notice the skybox leaks BUT only in one angle.
I tried experiementing a bit.
I tried remaking the skybox around this area , to check for any leaks on my own , used interlopers site to make sure my compile log doesnt have any errors etc. But hammer says that there are no leaks.
I noticed that the error happens only when you looked at the fence so i deleted it but still nothing.
here is a picture in hammer:

it's the first time i face such a weird problem and I honestly have no Idea what could be causing it.

 

Update: the only progress i made is that when I removed the 3d skybox entirely the leak gets fixed. does that ring any bells?