Reheating Hamburger Helper
I called General Mills, the makers of Hamburger Helper, and asked if there had been any changes to their recipes in the past 3 years. The representative (Thanks Kathy!) told me that the only recent change happened in 2016 when they stopped using artificial flavors and colors and switched to an all-natural formula. (see What does &quot;natural&quot; actually mean?)

I also visited the General Mills website and read the ingredients for all of the Hamburger Helper varieties. They are all thickened with cornstarch. Cornstarch does tend to thin out upon reheating, but I have no explanation of what could account for your change in experience (all other factors being the same). Look to what you’re doing differently, and methinks that there’s your answer.