Jean-Michaël Celerier

this could definitely be a cause indeed, the MSVC toolchain does not support mixing debug and release DLLs

just tried on msvc and seems to be alright there: 

I'll try with python 3.13.2 to see what happens

Okay, indeed here I'm getting a stall when doing import pylibremidi on 3.13

Also with 3.12, and also with msys's clang & python & .... 3.11 works fine everywhere.

I think I got a fix, it was some static variable that triggered too-early-loading of winrt

 :)