After changing the Display Name for a custom field, why does the old Display Name still show in Custom Fields dialog?
Why is the old Display Name still shown in the Custom fields dialog, even after I have changed this Display Name?
This can happen if you change the system locale - check that you have changed the Translated Display Name, and not only the Display Name.
Make sure that you change all translations especially if the languages are similar. For example, en-US and en-GB
Updated: Andrew Thompson