It's possible that something updated and caused a rift, or simply didn't install quite right originally. Can you give this a try:
Completely uninstall the PWA extension
Press the Save button in Atticus
Log out completely from Atticus using the link you find after clicking the Profile icon
Clear cache for Atticus specifically using the directions below:
How to clear cache just for Atticus:
In Chrome, open app.atticus.io
Go into Chrome Developer Tools
CMD+Option+I on a Mac
CTRL+Shift+I or F12 on Windows, Linux, and Chromebook
NOTE: You won’t need to do anything in developer tools, but you won’t see the Empty Cache and Hard Reload option if you don’t have developer tools open.
Right click on the Refresh button next to the address bar (left side of your screen)
Click "Empty Cache and Hard Reload" in the list of options, and you’re done. The cache for this website, and this website only, has been emptied.
That should bring back your normal screen and then you can close out of the Developer Tools box.
Reinstall the PWA Chrome extension from https://chrome.google.com/webstore/detail/prowritingaid-grammar-che/npnbdojkgkbcdfdjlfdmplppdphlhhcf