Proofreader does not work. SIerra/Pages '09 v4.3
I just updated my iMac (mid 2011) to SIerra, and updated my iWork '09 Suite (via the App Store). Now Proofreader does not work, although "Check Spelling as you Type" does. When I click on Proofreader... I just get an empty Proofreader window and a ping. I have the language set in System Prefs to the same language in the document (UK English). I have opened several other documents, same result. Any suggestions? Thank you.
iMac, macOS Sierra (10.12.2), Pages '09 v4.3