Copilot PDF summaries

After the last couple of days, with some PDFs, I've been experiencing an issue with Copilot saying it doesn't have access to a PDF that I'm trying to get it to summarise in Edge Canary. At other times, it works great. I've tried with old (months, years) PDFs, ones that I've created or received recently, and created new ones from Word and Excel files, and there doesn't seem to be any pattern to whether it works or not. 

I've tried it worth both the 'Summarise document' and 'key points' suggested actions in the Copilot sidebar - it makes no difference which I choose. The error can appear whichever one I select. 

Also, I noticed that with some PDFs, the PDF tool bar has the 'Ask Copilot' button, and in others, that button says 'Summarise'. They work the same, opening Copilot, and the same  intermittent issue occurs, regardless of which version of the button is showing.

Anyone else got this issue? Cheers!