Copilot fails to summarise an open document (in word)

Question

When I ask copilot to "summarise this doc", after a moment, it responds with "something went wrong. please try again in a moment". I attempted to ask the same question several times and rebooting, copilot persistently returns with the same error message. I have done this using both the 'copilot summary' capability up the top as well as in the side panel - see below images.