MSVC_RUNTIME_LIBRARY value 'MultiThreadedDebugDLL' not known for this ASM_MASM compiler.

I'm getting this while trying to configure my project. It's a new problem that only started today after using cmake version 3.15.0-rc2 and version 3.15.0-rc3. I also upgraded to the newest VS2019 build tools, but I think that part might not be relevant. Not sure.

I'm at a loss because there is nothing in any of the projects CMakeLists.txt that makes any mention of such a variable, etc.

EDIT: I see the new policy CMP0091. Reading up so I can try to fix.

I couldn't figure it out. Tried to manually set CMAKE_MSVC_RUNTIME_LIBRARY to each of the four values, but got the same exact error message (except it changed based on what setting I passed in), such that none of them were accepted. :(