I mark up PDFs all the time. In the last week or so, when choosing "Comments" and using the comment tools, my PDF page—and the red arrow boxes—just flash and flash. My goal is to add the comment boxes with the arrow from the tool bar, type annotations within the boxes, and be able to go back in to edit/update. I'm just getting incessant flashing now and can't do my job. IT has started to try different things, but no luck yet. Any advice??? Thank you.
Hope you are doing well and sorry for the trouble.
Would you mind sharing the version of the Acrobat DC you are using? To check the version go to Help > About Acrobat and make sure you have the recent version 22.1.20117 (Win), 20112 (Mac). Go to Help > Check for updates and reboot the computer once.
Also, check if it's a file-specific issue or not? Please try with a different PDF file and check. If the file is stored on a shared network/drive, please download it to your computer first an then try again.