[tavert]

were you missing compiler runtime libraries? like any code compiled with gcc anywhere that links the runtimes as shared libraries, they'll need to be present for executables to run. depending which variant of mingw-w64 you used, there are more runtime library dependencies than there used to be, like winpthreads for c++11 thread support.

[aepiepaey]

Fairly certain that wasn't the case.

As far as I could tell, the only DLLs the binaries referenced were msvcrt.dll and standard windows DLLs (KERNEL32, USER32, etc).

The application was also plain C.

Even if missing compiler runtime libraries were the issue, I would have expected the program crash or fail with an error message.