It would appear that if a ship does not have a shield, upon uncloaking the transparency of the craft remains. I'm assuming that the shield coming back on-line reverts the transparency back to normal, but this fails if there is no shield mounted. However, the ship is otherwise completely visible on the radar.
Really? Gonna test that.
But guess it's same case as when cloaking process interrupted by lacking of fuel, when ship hadn't reached full invisibility.
You're transparent only for those, who've seen you cloaking