*Edit: more info* She is an 8 yr old Australian Shepherd. We recently (3 months ago) had to PTS our other Aussie but just got Gromit (a 6 monthish mutt a month ago)*
Zoe has recently lost ALL motivation what so ever. She had gotten really bad listening wise recently with the addition of Gromit

and so we have been doing more training.
First I tried cheese and her E-collar, so I could reinforce those cues, and after a minute or two she just went completely mute to whatever I did, and was more interested in Gromit. I checked the fit of her collar and that the battery was still on, and it was. (Maybe the collar was not picking up the signal?).
I ended it after we had some response.
She used to be lightning fast on her commands. Now she won't do them unless they are enforced (hand on her rump or shoulders (not pushing just there)).
I tried again tonight with Salami, and she maybe paid attention for 5 minutes, but was having difficulty. I was working on looking at me when she heeled, but having her stand/sit next to me and I would say heel and give her the treat when she looked at me.
Once again she just tuned out, and so I tried to end it on an easy note and sat next to her so she would barely have to move her eyes (that were following my treat) and look at/near me. As soon as she got near my though she would swallow and look away.
Is this a dominance issue?
I was thinking of just doing *short* training sessions (30 secs at first!) and then building back up, but I'm confused at the sudden change in her. She doesn't really care that much about us (but still does) but is obsessed with Gromit. She had gotten better recently, as in coming to get pats when before she just only wanted to be with Gromit.
I need help! She isn't toy motivated, semi praise.
Before I used to play with her, but with Gromit (and they play all day long and rough...so my play I guess is boring) that doesn't work anymore!!!
Thanks for reading!