I have found (by myself with trying) a workarround:
You can engineer under certain conditions.
1. You have to fly to every engineer. (An engineer is buggy and does not appear on the planet)
2. You have to make sure in advance that you have ALL the materials you need for the module's engineering.
3. UNDER NO CIRCUMSTANCES is it allowed to display a level that can NOT be engineered!
This includes:
• Grayed-out levels because you have not completed the pre-stage yet.
• Levels for which a material would be missing / displayed in red.
It is recommended to use the mouse to navigate. As soon as you want to show a level that you can not engineer, the game bugs and you have to go back to the main menu.
Experimental effects are not affected.