Confirming the same issue here, but in my case it only appears to be happening if I’m using an image field.
The post will be duplicated if I do the following –
– create a new field group,
– add an image field,
– set visibility to (for example) show if post type is post
– create or open an existing post, click update
If I then edit the field group and change the field type from image to text, the problem goes away. At this point updating a post will not create a duplicate.
Changing the field type back to image will bring back the problem.
This was tested on a fresh install of 4.7.1 using ACF 5.5.4, default 2017 theme, and no other plugins activated.
I noticed the issue on a work in progress and from that can confirm that the issue persists when changing visibility conditions (change show if post to show if page, or show if post is “foo”, etc.).
The problem did not seem to affect image fields nested inside of repeaters.
Also, the duplicated posts are created and saved as child pages of the original post.
— Some Post
In my tests updating a child page would not create a duplicate, only updating the parent would cause another duplicate.
Hope this is helpful.
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