I had a fire in my kitchen, ever since then I have not been able to paint one wall (outside) without the 2 x 4’s outline showing through. I have painted multiple times, including paint with primer mixed in.
Never use a product that has primer added to it… these types of products are relatively new and DO NOT hold up in the long run… ALWAYS prime with the appropriate product in a separate application!
In your case use a Pigmented Shellac Sealer Primer… give it TWO Coats…
Next choose a high grade finish coat product like Sherwin Williams Classic-99 and apply TWO finish coats with about 1-2 hrs dry time in between… Good Luck