Media Source not active in Lens Calibration

As soon as I have a working SDI In and Out set in Media Profile, the Media Source in the Lens Calibration window does not work anymore. It shows my device but no picture. Yet I still have a picture outside of the Calibration window.

Restarting the Engine did not work. Not even after Creating a new Project. Only after reinstalling the Engine.
But as soon as I set up everything to be production ready, I can´t get an image in the Lens Cal window.

Think this is a Bug. A critical one…

Or does someone have a solution?