I am signed in to my Adobe account but when I select the "sign" button, I get the "retrieving your information" dialog but it never moves past that "waiting" graphic...
I have tried logging out and logging back in, making sure I am on the latest version of Acrobat Pro DC. Nothing gets me past the rotating square box graphic.
We apologize for the inconvenience caused and for delayed response. As per the description above, you are not able to sign in a PDF file using Acrobat Pro DC, Is that correct?
Please check for any pending updates of Acrobat Pro from Help>Check for updates, reboot the machine after the installation of updates.
Try repairing the installation files of Acrobat from Help>Repair installation, reboot the machine after the repair and see if this brings any difference.
You can also reset the preferences of Acrobat, to reset the preferences, refer to How to reset Acrobat Preference settings to default.
Make sure you are logged in with your current Adobe ID and password in Acrobat and complete the signature profile.
If the issue still persists, please remove Acrobat using the Acrobat cleaner tool Download Adobe Reader and Acrobat Cleaner Tool - Adobe Labs Reboot the machine and install Acrobat from Download Pro or Standard versions of Acrobat DC, 2017, XI, or X
Let us know how it goes.