The Lock Post Broadast plugin allows users to lock editing of posts / pages to only themselves and super admins. Other users are only given the option of viewing the locked post.
The plugin can be used when broadcasting or when simply editing a post, without broadcasting it.
It should be enough to uncheck the box and rebroadcast. Does the child post have the _broadcast_lock_post custom field set to anything?
At first I didn’t understand how Lock post worked and it caused this in the first place. I had a Page that was broadcasted to all my subsites from the main site because every site had the exact same page (exact same title and slug), only the content of the page was unique for all subsites. So I thought I’d “lock” the post from the main site so no one would accidentally rebroadcast it and overwrite the contents on subsites (I thought you could still edit the Page on subsites and only the original would be locked). But now I realize that I should use the Protect Child Properties plugin for that.
Great plugin btw!
The fastest and easiest way would be to modify this snippet.