Already found a solution myself, turned out to be an error because of CAD files linked to the model but turned off, so tu sum up, if you are not using a CAD link, unlink it from your model, not just turn it graphics off.
@Anonymous wrote:
These awful black lines appeard over the limits between elements. It´s neither a transparency or visibility issue, they just appeared from nowhere on all of my 3D views. Does anyone knows how to fix this? Thanks.