I am not really sure what is going wrong,
when running a config.empty.json file from /udata/config_empty.json everything works fine and I have a clean pass-through.
But when using a different file:
sushi -r -c /udata/config_play_vst3_desktop.json &  263 .... Error reading config file, invalid file: /udata/config_play_vst3_desktop.json
I get this error when everything else seems identical.
looking here I noticed I need to add the full path but I believe I am doing this already.
Can anyone help me with this problem?