With version 4.2, WordPress has started to update and fix its previous bugs of shared terms. For example, you have tags and categories named “News”. Those are then stored in a database under the same ID. The same applies to different custom types. In our case, for example, we have 2 custom types: Services and Testimonials. These are categorized in taxonomy called “Categories” such as many other custom types. Both then share the same ID for their terms. Therefore, in the new WordPress versions, all taxonomies (category, location, tags, etc.) will be now stored separately so that their terms will not share the same ID. We call this action “split terms”.
The reason you need this fix is that when your website wants to show a term (certain category), it will call a new ID while it doesn’t know that the term was stored under the old, shared one. This causes the website not being able to show anything as it can’t find what it’s looking for. So, this plugin finds all such shared terms and assigns them to the new correct ID.