Help with Error during WebSocket handshake: Unexpected response code: 404

Everything works except, when using companion, I can’t seem to pull down the images. I can see them, authenticate etc. - but selecting them and actioning that seems to produce error;

WebSocket connection to ‘wss:/domain.om/api/307fb067-0648-42ac-9ed9-c82fcf07ce64’ failed: Error during WebSocket handshake: Unexpected response code: 404

I can’t seem to get by this, would anyone have any guidance?

Thanks!