Hi James,
can you try it with leading captial letters? I reproduced this in stock conditions – lowercase was fine, capital letters are required to trigger the translation. Anything that equals an internal wordpress label is being translated.
No translation plugin!
Problem persists with ACF as the only installed plugin – just the language of wordpress installation is set to german …
For example: wp-admin menu “Appearance” is called “Design” in the german translation (ridiculous, right?). In consequence, if I name a custom field “appearance” its name changes to “design” right after I publish.
