They showed up on radar, problem was by the time the germans got the heads up, engines hot and altitude, the mossies were gone...long gone..WAY gone.
This is basically correct. Detecting and effecting an intercept are two very different things.
There were no WWII aircraft that were "stealth" capable. To the best of my knowledge, the first "stealth" capable aircraft was the F-117.
A note on a myth that annoys me, the Ho229 most certainly was not "stealth" capable. Being a flying wing in no way makes an aircraft difficult to detect with radar. The B-2 is made of special materials and has very special shaping to achieve its radar aborbing qualities. The Ho229 had none of those things.