Hi,
I just wanted to share this with anyone with the same problem.
Yesterday, I did a fresh install on my work user account and noticed that every time c_cpp_properties.json rebuilt, I got a couple of errors complaining that: platformio/packages/framework-arduinoespressif32/tools/sdk/esp32/include/config", was missing. Later, I did a fresh install on my Macbook and got exactly the same error. I was able to resolve the problem by manually copying the config from an earlier installation on my personal user account, so it looks like there is an error somewhere in the latest installation routine / intellisense rebuild(?).
Andy