I'm not sure whether it's relevant in this case, but in general you
don't want to ignore the FRAME argument with after-make-frame-functions,
otherwise you don't know which frame is selected when your code is
I'll keep that in mind. For the reason in that comment, after-make-frame-functions did not work for me, so I had stopped using it.
Also, my workflow always uses only 1 frame. So there wasn't the problem of selecting the frame (I think it selected the one and only frame then open by default).
Though, it's good to know the right way of using that frame argument.