This bug has been around for years. In some cases, users can work around it by clicking "OK," then pressing the render button, stopping it, and switching back to interactive rendering.
However, at times, there is no workaround, clicking "OK" does nothing, and if the user tries to start interactive rendering again, the message reappears in an endless loop.
Additionally, the error message is often incorrect, as Corona is not actually rendering when it appears, making the warning misleading.
Possible Fix:
When the user clicks "OK," the system should check for any active CPU cores running a render process and force them to stop, allowing new commands such as rendering or interactive rendering to proceed.