Please follow the below steps.
> Go to Lightroom > Preferences.
> Click on the General tab
> Uncheck “Show ‘Add Photos’ Screen”
> Restart Lightroom
Let me know if this helps.
If not, try changing the destination folder to a different location(e.g. to Desktop).
Thank you for the response! It still doesn't work. I dont even get the export dialog box when I select export in the menu.
You might need to roll back Lightroom to the previous version. Instructions here: How do I roll back to Lightroom 2015.1.1 or Lightroom 6.1.1? Many people are experiencing major stability issues and import and export problems with the latest update even after the extra 2.1 update. Since you are on a deadline that's probably the best way to go.
Thank you! I just tried this and it worked perfectly. Much appreciated you two!