Hello Alf , and welcome on this board.
sorry you're encountering this issue.
Could you please check the connections on the Unit? if you look at the insert connectors at the back of the AudioFuse, you'll see, from left to right , INSERT 2 and INSERT 1. Could it be that these connections have been inverted?
Sorry for this dumb question, but most of the users who didn't manage to make the inserts work did actually inverted the connections.
Hope it helps,
Looking forward to read you,
best,