Can you please try doing what’s described below:
In your WPEngine account/site settings, find the section to add url redirects. ‘Edit URL Redirect’ may be its title. If you cant find it, just ask WPEngine support.
Then in that interface, enter the following values to relevant fields:
Redirect Name:
Patreon WordPress Image Protection
Domain:
All domains
Source :
^/wp-content/uploads/((.*?)(.png|.jpg|.gif|.jpeg|.bmp))$
Destination:
index.php?patreon_action=serve_patron_only_image&patron_only_image=$1
Then, save.
It may take some while for this rule to take effect. After waiting for 15-20 minutes, just try viewing a protected image. Or a protected image embedded in a protected post.