Yes, I am.
I can’t believe I’ve never seen that before?! Thank you 
That does do what I want, although if it could be done through Shortcuts without having to open Dropbox (and automatically selecting the destination folder etc) that’d be even better. Any ideas why the PDF doesn’t get the content saved when trying via Shortcuts?
I wasn’t aware of this new limit until setting up my new phone today, but no, I’m not over that limit anymore. I had the same issue on my old phone too, before it warned me about the limit.