What is your opinion on Feed only or No Feed Pmax?With so many business struggling with low conversion rates on their stores what is your take on a more manual/organic approach to managing Pmax and other types of campaigns?

Yes, seems to be a bug. In my particular case the Collection condition was a product tag and I wanted to remove the product from the collection. I was able to fix it by adding the tag again, saving the product and then removing the tag again. 

experiencing this same issue. I have noticed that sometimes automated collections take some time to update on the frontend but now it is just not updating.