I’ve found with most crockpot recipes you don’t need NEARLY the amount of time stated. I have a very powerful crockpot & I only had to do the breasts for a fraction of the time. Check the breast after 1-2 hrs on low
Also I thinned the sauce CONSIDERABLY. It would have been WAYYY too thick. Add a bit of stock little by little to make it a more palatable sauce (a bit like thinner Alfredo sauce)