Try selecting <inherit from parent or project defaults> for the Enable Minimal Rebuild option (under C/C++ > Code Generation). After this, the option should show No (/Gm-), not in bold. Make sure you do this for your project(s) (you could have several projects in the solution), and all property pages they inherit from.
I had the same problem using Visual Studio 2019, in the end the problem was in a second project I had in the same solution, that had the option set to Yes (/Gm).