Once you start typing into the "Format" field under the "Quest header settings" section in the Butter Quest Tracker config, an "Okay" button appears within the field (see marked on the attached screenshot). The problem with this is that if the text you enter in this field is longer than the space before the "Okay" button, you will be typing behind the button so you cannot see what you're typing and you cannot see your cursor position either.

Hey @fleetcommand, thanks for taking the time to submit an issue!

Unfortunately I was already away of this, however AFAIK it's a limitation of the library (AceConfig) I'm currently using for the options dialog.

Fixing it at this point would require quite a bit of rework.
I'm going to be reworking it at some point to not use AceConfig since it's
caused other issues related to various screen resolutions and Addons.