I am playing with the default Save To Dropbox action (“Save to timestamped file in Dropbox.”).
I was able to authorize against Dropbox, and then Drafts created the file as expected, but now a day later when I run the action it always returns non-success (i.e. it shows the exclamation mark).
I have already tried to delete the authorization and re-authorize against Dropbox, but with the same result: Just a red exclamation mark next to the Save To Dropbox name, but nothing else. I have no idea why.
Retry on a solid data connection to confirm your suspicion.
As far as I know, there isn’t a way to display the action log to the user, but if the action fails you can set the notification to be displayed (if it isn’t already). That should be a prompt for the user to check the log.