Hope you are doing well and sorry for the trouble. As described the application is freezing and not responding on using the comment function.
Is this a behavior with a particular PDF file or with all the PDFs that you try to comment? 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 and then try to comment it and check.
Please try to repair the installation (Win only) from the help menu and reboot the computer once.
You may also try to turn off the protected mode for testing (Win Only) go to Edit > Preferences > Enhanced Security > Uncheck 'Enable Protected mode at startup' , Turn off the protected mode and uncheck 'Enhanced Security' > Click OK and reboot the computer once