To regain full functionality, I found it necessary to download the most recent version of Evernote and install (I did not need to do uninstall first for this to work). Despite attempting to close fullscreen (F11) and the window (Alt + F4), as well as using task manager options, I encountered no success. It's my belief that the updater was possibly stuck, prompting the need for manual intervention. While I didn't verify this, I hope this helps anyone in their troubleshooting journey.