LR Mobile only syncs with One catalog on One computer. Even if you copy a catalog from the computer that is currently synced with LR Mobile to another computer and then sync that second computer up with LR Mobile, using the same catalog, it will Un-Sync the first computer.
LR Mobile looks for a Unique ID that is given to a catalog. Every time you move a catalog from one computer to another it gets a different Unique ID. So although it is the exact same catalog on both computers the Unique ID is different and LR Mobile can only sync with one Unique ID at a time.
So basically you are SOL.
IMHO LR Mobile is a bad joke played on Pro photographer and advanced amateurs, IE the people that made LR what it is today. It was thought up for Home Users that take Snapshots mostly their Phones.
That's interesting. Somehow somewhere I though you can work on Desktop, sync to mobile, take a laptop on your trip do your thing, or make edits on existing collections, and come back home and its all sync'd to your desktop. Basically I thought creative cloud magically syncs Desktop, mobile, and laptop.
So, for my needs, I am better off sync'ing catalogs and taking my photos on ext HD then. I don't do much editing on phone. I may use it to see pics on the go. That's it.
You can do that but not with LR Mobile.
To do what you are taking about you have to built Smart Previews and have the exact same catalog on both computers including the Lightroom Catalog Previews.lrdata folder and the Lightroom Catalog Smart Previews.lrdata folder. Then when away from all the images you can edit images and then when you get back home and the catalog can sync up with the Real images it applies the edits.
LR Mobile is for syncing One Catalog from One computer to Multiple mobile devices, Apple iOS and Android devices. It doesn't work with a Microsoft Surface because the Surface runs the full Windows operating system. The mobile devices has to be an iOS or Android device.
OK So copy catalog, smart preview and post them on same tree line of folder on laptop or PC. And hook up Ext HD. Is that right?
Yes kind of. Sorry but I know this works but I have never used the Smart Previews feature so I have no first hand knowledge of how to actually use it.
Google "Using Smart Previews in Lightroom" and I bet you get a ton of hits including some online tutorials on how and what to do.
But if all your images are on an external drive you could just take that drive with you.
Best of luck to you.
Great. Big help. Appreciate it. Best wishes