I am getting an error "404 specified folder not found" error when sending an email from a shared mailbox in a flow. The same feature works fine in other flows - there are at least half a dozen of them, all using the same shared mailbox. And if I recreate the step in a new flow it works fine.
I have the necessary access to the shared mailbox, the flows all use my user connections and there are no co-owners. The flow with the error is triggered by changing a Sharepoint list item so there's no potential conflict with PowerApps.
It has worked just fine for quite a while and now it doesn't. I just cannot see why it's stopped working.