Media disappears when saving a post

I think i found a bug. A client was doing these steps and i was able to reproduce it.

– she logged in and pressed edit at a post that i made (so she’s editing it as a different user than the user that created it)
– opened the ‘media’ page in a new tab
– uploaded 5 images
– went back to the other tab, added the images to an ACF (Advanced Custom Fields) repeater field
– pressed update

Then all images vanished, and also from the media library. When i opened a page where i can add an ACF page link, all these images where listed as pages / inherit. So i think ‘Post type switcher’ changes the status/type of the attachment.
It must have to do with ‘Post type switcher’ because i repeated these steps again and again with a backup of the database, and when i disabled ‘Post type switcher’ the problem disappeared.

A screencast showing it:
https://www.dropbox.com/s/gxnvjjdk469az23/post_type_switcher_bug.mp4?dl=0