The color labels in the Pages panel do not appear. When I right-click a page and go to the Page Attributes > Color Label, the first section for 'None' and 'Use Master Color' are grayed out. When I select a color nothing happens. I tried 'Override All Master Items' and set 'Apply Master Pages' to 'None', but that didn't work either.
Have you rebuilt your preferences? Hold down the Cntl-Alt-Shift keys or Cmd-Cntl-Opt-Shift keys when starting InDesign.
Try saving as IDML and reopen in InDesign.
Otherwise, is there any chance you could put the file in the Creative Cloud folder and share the link? You can make a copy and delete any sensitive material if necessary.