Ok, that's not a standard Confluence layout, it's a theme. You'll need to tell us which theming add-on you are using here, and which theme it is (It might also be a simple standalone theme, but my instinct is that it's one of the big theming add-ons - Refined, Brikit or Themebuilder)
The "standard" edit is Confluence's "edit entire page" which the theme links to. What you've said is broken is the theme's "section edit" function. I'd try reading the log to see if there are theme related errors in there when people try to edit a section, but I'm afraid this probably needs to go to the vendor for debugging.
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