Mail drafts not saving
I'm having a problem with Mail, using OS Sierra (10.12.6), Mail 10.3 and gmail. It's no longer saving drafts of my emails. I'll compose an email, then want to save it as a draft - so click Save on the "Save as draft?" dialogue....then - nothing. Nothing in my draft folder.
Actually, nothing in *either* of my draft folders, as there are two. One is under "Mailboxes" - along with VIPs, Sent, Junk, Trash and All Mail. The other is under "On My Mac" with just one other folder, Recovered Messages. Both folder names are followed by the name of my gmail account, so looks like this: Drafts (gmailname).
The gmail drafts folder does have a few drafts from a few months ago, back when this was working. The other has nothing in it. I'd like to be able to retrieve drafts from other devices, so whichever folder would enable that is preferred.
I did switch computers about a month ago, from a MacBook Pro running OS X Yosemite (10.10.5) to a Mac mini running Sierra. Can't say for sure that's when this started, but it's possible (maybe likely).
One other thing: in other strings on similar problems, there was advice about the ensuring drafts were saved on server in Preferences. I don't see that option anymore in Preferences. Here's what I got:
Any help would be appreciated. Thanks.
Mac mini, macOS Sierra (10.12.6), Mac mini late 2014