I have 6 octoprint instances on Raspberry Pis. Some have been running and updating themselves for over a year, 2 were built yesterday from scratch.
Every single one has the application keys plugin installed. Zero of them have any of the application key options you are showing from screenshots and wikis.
I am willing to work with you on any of this, screenshots, logs, whatever.
EDIT: Charlie, Please update your documentation to show the photos of the user settings you mention. I finally found the page, but it is by clicking the username in the top right and then user settings. Until you generate your first user key, there is no way to generate a key via the settings panel which will confuse your userbase.
Photo attached for reference , feel free to use in Documentation.