Appears to be a regression since versions after 2.0.4. Tried to update to 2.6.3 but having troubles with Mix_LoadMUS_RW on module files (in this case an IT module). I tried compiling the 2.6.3 source myself using CMake and Visual Studio so I could debug it properly myself, but I get different results than what happens with the official releases.
How are official SDL_mixer releases being compiled? I'd like to be able to figure out exactly what's going wrong here that modules are considered an unrecognised format, as maybe then I can help fix the issue.