Bad news: the new version of PyOtherSide included in Iijoki seems significantly broken, at least with respect to how I'm using it. It's somewhat difficult or at least seriously inconvenient to work around, so it might take a while to fix this.

https://together.jolla.com/question/156736/

Could someone still using the previous version of SFOS download and share the RPM of "pyotherside-qml-plugin-python3-qt5"? Downgrading to that could be a temporary work-around.

There might be other problems with Iijoki as well, but I'd need this fixed before I can proceed.