I make roasts in the slow cooker all the time and never had this happen, whether I'm cooking quickly in a few hours or longer.... about 5-7 hours. I was thinking malfunction like some others, but the fact that the meat overcooked leaves me wondering why the veggies were undercooked (or you could say they were al dente
Like I mentioned in another topic, I normally left the veggies on top of the meat and only recently started putting just the carrots on the bottom to keep the meat somewhat out of the juices. Which leads me to ask this dumb question: You did add some kind of liquid, right?
I went over your recipe several times and the only liquid
I saw was maple syrup. And I wouldn't call a syrup a liquid. I saw you used powdered onion, too. I always use real onions plus some water. Real onions give off a lot of juice.
Just a suggestion..... And you did leave the lid on too, right? If you kept checking it all the time you would be letting out the steam from whatever liquids you had in there.