I too am having a very similar issue (I think). Here is a bit of the build log where cmake kindly informs me where to go to post about the issue:
System is unknown to cmake, create:
(https://github.com/ctc-oss/omega-edit/runs/4889162055?check_suite_focus=true#step:5:453)Platform/MINGW64_NT-10.0-17763 to use this system, please post your config file on discourse.cmake.org so it can be added to cmake
I’m new to the forums and relatively new to cmake. Things started getting complex when I vendor’ed in gRPC (which also uses cmake) as a submodule that I need to link against. Any assistance would be greatly appreciated. Thanks!