Ok good news, i think you can stop searching for the error.
This item has to be defined and then the others work as well, although i don’t use it somewhere else.
String St_Tv_PlayingURI_Lr "Playing URI" { channel="sony:scalar:mysonytv:avContent#pl_uri-main" }
It would be nice to know if you can reproduce the error. If yes maybe this could and should be fixed.
Why should one define items as condition that other items work as expected. Especially with this vast number of channels within this binding… It was pure luck that i found this out.