I've just been troubleshooting the following issue:
- On a multi-site install, site administrators are unable to save the meta description in the Yoast SEO meta box
- The admin user can edit the description, however after saving the post, the description reverts back to it's previous value
- Super Admins are able to update the meta descriptions as normal
After kicking off with the usual default theme and one by one plugin activation, I have found that this issue only occurs when the WPMU's Support System Plugin is also Network Activated.
I'll raise this with Yoast as well but if the WPMU devs could look into it as well that'd be grand.