Ideas
There is a similar issue on Mac (which I reported here [CD] Cannot enter breed name, box greyed out | EA Forums - 12522619 ) although on Mac, the breed name cannot be entered (as it appears to be able to be on PC) and the randomise button does nothing (which fixes the unrelated console issue).
I am a pc player and the randomize works just fine for me and that is why I had posted it as a work around in another post. I did realize just now that I forgot to list two steps. I guess because most of us know to do it, but if you're like me sometimes you just don't think of stuff you're used to doing all of the time. Just wanted to point this out as I didn't realize the thread I posted it was primarily for console. I will pay better attention going forward and I felt it was important to pipe up here to let the powers that be know that it works for me as a pc user.
Updated steps that work for me as a pc user are....
Before entering CAS, make sure to turn on "testingcheats on" and "cas.fulleditmode"
In CAS by the check mark and X is a little dice button and to the left of the dice button is a little arrow button. Click the little arrow button and make it so that it will not randomize anything except pet clothes. Then click the dice button. it will put some outfit or whatever on your pet but that is ok for now. It should also set the pet breed as mixed or allow you to select one, but I think it will just set it as mixed. Then you can remove the clothes or select the clothes you want on your pet and save. So far this method has worked for me with no worry as to changing the look of my pet.
Also it is not just adopt a pet as most of my sim's pets were strays and some of them had the issue. I also stole a pet from an npc's home and it had the issue too. Anyhow, just wanted to update this with all steps needed in case it can help someone. I go into CAS all of the time and forget to turn on the full edit mode 😗