Terrain appears black in some spots after bake

Hello guys. I`m still a noob regarding light bake etc.
i`m trying to reach the infamous 100FRAME for a VR game
i had some problems after bake.

■Situation:

- Before bake light can see everithing normally in the editor
- After Bake the textures that should appears in full resolution, one portion of the texture appears black
- If i change the base map distance i can get colors but in low resolution

■Question:

- What can i do to fix this problem?
- Is there a problem related to the texture?
- Is there a problem related to the bake settings?

 

UPDATE:

I found a new alert i think is related.
Even if i have alreade set mip maps and repeat as wrap it keeps to give me the alert....

 

UPDATE:

after bake (or before)
removing the the terrain mask map, that wasn`t RGB+A the color come bake again.
After that i have to fix the AO, smoothness, metallic

 

Cool.