The same problem happens with me and i think the it’s in the API version, as I have an api with old version which is working properly, but with version 2.12 is facing issues.

It only submits to profile, and can not submit to pages or groups.

In your case try this:

From your facebook account choose your target page:

Settings >> General >> Visitor Posts >>> then check “Allow photo and video posts”

the problem here is that you will be posting to your page as a visitor

I hope the plugin developer respond to this thread and fix this issue

I hope