Dear Max,
deleting .platformio helped fix the problem.
However, when I re-installed platformIO, I stumbled into the next problem:
“platform = raspberrypi” in platformio.ini generated an error message regarding “board = rpipicow”.
When I used your GitHub repository instead (“platform = https://github.com/maxgerhardt/platform-raspberrypi.git”) it went through o.k.
Anyhow, thank you again for all your help!!
Best regards
Ludwin