enctype="multipart/form-data" is defined.
this is not the problem.
The problem here is that the file uploads are complex in ajax. I've been searching, but the problem comes from javascript not handling properly.
I will have a look.
Some help here :
abandon.ie/notebook/simple-file-uploads-using-jquery-ajax
Or here:
tutorialzine.com/2013/05/mini-ajax-file-upload-form/
But this one is more complex, so I prefer to implement the simpliest one.
Also :
hayageek.com/ajax-file-upload-jquery/
code.tutsplus.com/tutorials/uploading-fi...with-ajax--net-21077
All those uploaders will not work with IE for the moment.
So anyway, you should think to build an alternative. the modal should not be the only way to upload files.
This is not a limitation of Cook, but cook has a problem I will try to fix because it seems to never works, even out of IE.