After fighting a whole day with the bug on the site, leaving here as bug plus Search Engines.
ACF is incompatible with Multisite if you’ll add a new field of type “Media”.
It’s a known problem that WP stores Network users and their meta in one table for all sites, however, ACF doesn’t personalise those fields per site.
It’s ok for text files, however, Media file is a relationship so what’s happening is in your user meta field you’ll have Media ID stored that will work on this particular website, but when you go to another site in network it will try to pick a Media file from this site creating a conflict.
Steps to reproduce:
– Create extra user field “User Logo” in WordPress Multisite, type of image
– Create user Bob on one of the Network sites, say site A
– Assign Bob also as a user to Network site B
– Go to site B and view user Bob. If you’re lucky you’ll see field empty, because Media ID didn’t match anything on this site. If you’re unlucky and media matched something, you’ll see a random image under User Logo.
