When I re-enter a singelplayer world or restart my server this happens to all my wires.

They go back to normal after block update.

Not in theme, this bundled cables was other before (in 1.7.10, as i seen, the corners has been clearly visible as wires continue, without colors overlap) it is bug?

This is a known issue with FMP. It is being looked into and is the highest priority issue to be fixed.

Does it cause cables to be disconnected or is it just a visual bug?

Found the issue, it appears a fix i attempted yesterday, caused some logic to fire that shouldn't have.

Not a visual bug. Wires actually loose connections because they are updating their connections before things around them are loaded.

A little delay on worldload? Also this happened with chunk reload? Or only world entering?

Its not that simple, i'm looking in to the issue, its extremely complex, and its nothing in ProjectRed, its purely an FMP issue.