I've got Excel Online with the Flows add-in installed, but it does not seems to be working. When I select the row, the 'Run flow' button is not visible on the right panel. What can I do to make them work properly?

I've got Excel Online with the Flows add-in installed, but it does not seems to be working. When I select the row, the 'Run flow' button is not visible on the right panel. What can I do to make them work properly?