Is this an issue with a particular PDF file or with all the PDFs? Please try with a different PDF file and check.
Would you mind sharing the version of the Reader DC and the OS you are using? To check the version go to Help > About Acrobat and make sure you have the most recent installed. Go to help > Check for updates and reboot the computer once.
Also try to repair the installation from the help menu (Win Only) and check.