Sync Mac Mini and Macbook Pro with Dropbox

Very much hoping someone can help with this, I would appreciate any help.
I recently upgraded to Scrivener 3 and simply want to sync work across a MacMini and Macbook Pro both running latest version of osHigh Sierra.
i am currently running Scrivener 2 and Scrivener 3 side by side as I transfer work.
I have installed Dropbox on both machines — and the dropbox icon appears in both Finder sidebars. The Dropbox icon appears in both menu bars EXCEPT, ironically, when in Scrivener 3 on the Macbook Pro (it appears in the menu bar for al other apps except Scrivener 3)
I have read the User Manual, specifically the chapter Scrivener Everywhere — which seems more concerned with iOS synching than mac to mac synching.
I have been all over the internet, watched a few youtube videos, and trawled through the Forums here.
This is where I’m at:
I created a folders named Local Documents in my home folders. Inside the Local Documents folders I created a folder named, Scrivener Backups on both machines.
(All my other documents, desktop and photos etc are on iCloud Drive. There are NO Scrivener files on my iCloud Drive )
Go to Scrivener Preferences — Back Up and set the back up location as Local Documents/Scrivener Backups

  1. I open Current work in Scrivener 3 on the Mac Mini via the Recent dropdown. Opens no problem. Add text. Close project. Wait for Dropbox sync.
  2. After a flurry of Dropbox notifications I open Scrivener 3 on MacBook Pro and open Current work via Recent dropdown and get message: Project not in a recommended save location.

Before I proceed with transferring any more Scrivener 2 files I want to get the back ups and synching sorted.
What I’d like is:
a) To know exactly what is that I’m doing wrong.
b) A step by step guide to syncing a Macbook Pro with a Mac Mini via Dropbox.
c) To know why Dropbox icon disappears from Macbook Pro menu bar when in Scrivener 3.

I’m not interested in syncing with iPhones, iPads or iPods — just a Macbook Pro and Mac Mini.
If you can help I would really very much appreciate it. Many thanks .

The “not in a recommended location” message indicates that your backups and your live project are in the same folder. So please double check your configuration. I’d also try opening the project directly from Finder, rather than from the Recent Projects menu. Recent Projects can point you to old versions or old locations, especially if the project has been moved or renamed. (Once you resolve the issue, you can clear the menu and let Scrivener rebuild it.)

It’s not a Dropbox-related error, though, so it doesn’t indicate whether or not the project is actually syncing. Is it?

Is Scrivener in Full Screen mode on the MacBook? If so, the entire menu bar will be hidden, not just the Dropbox icon. That’s normal, and doesn’t indicate any kind of issue.