If you have some fader values already assigned and saved, but then you click on the fixture all of the values get reset to 0. See screenshots attached. I believe this bug was introduced after the 'fixture attribute manager' was added.
I've raised the same issue. I've also emailed Mathew at enttec support. There is a workaround, click on the top of the fader it's self. I use this to lock/unlock faders for a moving head fixture.