The developer posted a comment on the link you provided, copied below.
Hi guys
Thanks for the tag.
It sounds like using the variable $page is causing issues. Please note this can’t be replicated 100% of the time, so there must be something else to this story which is causing some function.php files to modify a global var instead of a local one.
A simple fix is to place your ACF code within an action or function to avoid namespace issues!
