Is this a behavior with a particular PDF file or with all the PDFs? 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 locally and try again.
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 22.1.20085 installed. Go to Help > Check for updates and reboot the computer once.