Hope you are doing well and sorry for the trouble. As described you won't get any menu button as shown in the attached screenshot.
Would you mind sharing the version of the Adobe Acrobat/Reader DC you are using? To check the version go to Help > About Acrobat and make sure you have the latest version 21.01.20145 installed. Go to Help > Check for Updates and reboot the computer once.
Are you on Mac or Windows Machine and what is the version of the OS? Please check for any missing/pending updates and try updating the OS and see if that helps.
Please try to repair installation (Win Only) go to Help > Repair Installation and reboot the computer.