What does WhereUsed detect?
WhereUsed will scan your site and detect where posts, pages, attachments, blocks, links, and iframes are referenced throughout your site or multisite environment. It does not detect where shortcodes are used at this time.
Does WhereUsed scan theme or plugin code for references.
No. If you have images or links hardcoded into your theme or in a plugin, WhereUsed will not know about it.
Where does a scan look for references?
When you run a full scan, it will first look at your settings to determine what is scanned. From there it will scan users, user meta, posts (even custom post types), post meta, and menus. It will not scan custom database tables for references.
How long does a full scan take?
That depends entirely what your settings are telling it to scan and how large the website is. Small sites can typically be scanned within a few mins, while large sites may take a couple of hours. Don’t worry if your scan takes a long time. The scan runs in the background and your can navigate away and do something else.
Is WhereUsed compatible with my custom Gutenberg block?
Yes, partially. It will detect where your custom block is used, but it does not know how your block works. If your block references another post by ID or link, WhereUsed will not detect the reference.
You can make your custom block fully compatible with WhereUsed by using a hook.
Is WhereUsed compatible with Advanced Custom Fields (ACF)?
Yes. WhereUsed scans post meta (even post meta created by ACF). There is a caveat to that. ACF may associate a value of a custom field to another post using a post ID. At the moment, WhereUsed does not know that the value (a number) is indeed a post ID. It could be a count or something else. The same goes for a custom field that is added by PHP code.
You can make your custom field fully compatible with WhereUsed by using this hook.