I have a device (sonoff basic smart switch) which I can control directly from the eWeLink Smart Home menu on my home assistant page by clicking on its on / off slider.
If instead of clicking on the little slider to turn it on I click on the rest of the button, to see the details or edit it I get a drop down appearing whiah says “Only the device owner can edit.”
I had the same issue. I just logged out on the top right of the ewelink menu page and logged in again with my ewelink account (again top right on the ewelink page). Worked for me.