LE12.0.2: strange behaviour when trying to connect to hidden SSID

I just updated from LE12.0.1 to LE 12.0.2 on RPI3
Previously I connected to my hidden SSID using systemd service like described here: https://wiki.libreelec.tv/configuration/hidden-wifi

Now after updating this still works, but only, if no USB-drive is connected.
If a USB-drive is connected I get a "failed to start hidden-ssid.service" - every time.
If I disconnect the USB-drive and restart, LE can connect to SSID without any problem.
Using LE12.0.1 with same hardware is working fine with/without USB-drive.

When adding this to autostart.sh, I can also connect with LE12.0.2 and USB-drive:
/usr/bin/iwctl --passphrase <PWD> station wlan0 connect-hidden <SSID>

So, it seems like something changed in startup-sequence, making systemd-service described in Wiki not working any more.
How to startup systemd-service correctly for hidden SSID when using LE12.0.2?