Since I generally use a language other than English in WordPress, I have just noticed that there are hidden tabs in the preferences under Cornerstone.

The reason is that the tabs are cut off in the non-English language version.
German Version:
(the small dots and lines are the rest of the tabs)

It depends on the height of the preset window how far the tabs are cropped:

The tabs are only displayed in full if the preset window is high enough. However, the gray background only appears in the English version.
(pro Version 6.4.2)