OnOff-Shim not booting on PI Zero W with on PIOS (version 2020-0527)

Soldered On-Off-Shim on header, place it on top of Pi Zero W. Try to boot with PIOS Lite (version 27th May 2020). Green led of PI Zero goes off, after a few moments (10-15 secs). PI Zero is not visible on Wifi. Without the OnOff-Shim, the Pi Zero boots successfully.

The installation of the OnOff-Shim software showed no errors and seems successfully.

Any idea why it is not working?
Is software compatible with PIOS/Buster?

Thanks for any pointers, Peter