If the whole content of the VFB becomes black as soon as you switch to the Interactive LightMix render element or if you just open the LightMix tab and try to change some of the LightMix values:
- Make sure that the intensities of the lights listed in the LightMix tab are not set to 0, and that their colors are non-black.
- Make sure that there are no leftover render elements in your scene from some other renderer (this may happen if your scene was originally created with a different renderer, and then converted to Corona). If you can find such elements in Render Setup > Render Elements, removing them should solve the issue.
If the above solutions do not seem to help, or if you are experiencing some other issue, please contact us.