Hey to fix this message error which happens when you try to load any lib in version 1.2.3 :

I just had to copy all the dll files in ocamlms64\lib\ocaml\stublibs to ocamlms64\lib. Does it help you to know where the bug is coming from ?
If no maybe that you should consider to change the released .zip file in order to do the move files trick for everyone 👍