I have mixed results using cornstarch. You could try using a dry roux. It can be made on the stovetop, in the oven or microwave. Do an Internet search and find the method that works best for you. It's simply toasted flour that can be used to thicken sauces, soups, gumbo, or other thin liquids into gravy. I keep it in a jar in my pantry.
No need to start from scratch. Tony Chachere’s Creole Brown Gravy Mix is a quick and easy way to make the perfect gravy. With Creole spices already mixed in, the flavor will enhance your favorite meals.
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They also make a white gravymix and a dry roux mix.
The ratio of cornstarch to room temperature liquid to make the slurry is 1:1. Bring instant pot liquid to a boil. Then slowly add slurry, stirring all the ti.e until gravy texture.
You are right. Your IP is cursed. I make gravy and it thickens every time! Seriously, do you know how much liquid and cornstarch you are using? Could you be misjudging the quantities?
@baptistgirl21 Depending on the recipe, it's usually 2-3 tsp dissolved in minimal amount of water or wine. More if the recipe has used more than 1-2 cups of liquid.
@bushra well, maybe try pouring the liquid into whatever kind of pan you would normally use for gravy in case you are underestimating the quantity of liquid. I’d usually make about 1.5 cups of gravy and use two heaped tsp of thickener.