PlatformIO IDE doesn't recognize "genericSTM32F103RC"

Why does’t IDE recognize `“genericSTM32F103RC” ? I’ve tried everything I can think of (total amateur) with no luck. Can anyone help?

Do you have an error message or a screenshot to show that the problem is?

pio init -b genericSTM32F103RC

works on my machine just fine.

That’s a different thing. As a value for default_envs, you can only give the name of an environment that exists in the platformio.ini (or .ini files it includes). So, if there is no [env: genericSTM32F103RC], you cannot do default_envs = genericSTM32F103RC.

The Marlin project contains lots of environments, some of which are STM32F103RC based. In particular, you seem to be working with a SKR Mini E3 V2.0, judging from the name of the workspace. The official repository for that device’s firmware device is already setup correctly:

So I’m not sure why you deviated from the good defaults to something that doesn’t work.