however other people I send the file to can see the black. Nothing has changed, no updates in Indesign or Acrobat since this started. Your help is appreciated. When I copy and paste only the black text into a new file and export the pdf then it shows up. In the file it doesn't show in, it is not turned off for printing. No layers. It is not covered up by anything. This is happening with all my files.
Without you providing a sample PDF file exhibiting this problem with full and detailed information as to how you created the PDF file from InDesign (including all settings), there is nothing that we can do to assist you here. Provide those (you can attach a file in these communities) and hopefully someone can assist you.