Flutter device selection not showing up (target selector)

in one of my Flutter project I cannot any longer see a target selector to select the device It is interesting because if I open another project the selector is there so there must be an issue with my first project or a setting I need to adjust...

Any help? How can I have my device selector back???

I had one Flutter project that always opened without the "Flutter Device Selection" drop-down and the "Run 'main.dart'" menu item was always greyed out. Other projects worked fine. After following the steps below, the problematic project could build and run in the emulator properly.

• close the project in Android Studio
• rename or delete the .idea folder in the root of your project
• open the project again