P: Include additional metadata in XMP (flags, collections, VC's, etc.)

When I upgraded from LR3 to LR6 things went haywire and long story short I had to recreate all of my catalogs in LR6 and manually transfer over changes I made in LR3. I've never used the export catalog feature before so I need to learn about it and test it. 

Thanks for the suggestions.

I presently have LR 3 & LR 6 installed on my computer and wanted to test what exactly is saved in XMP files. Every change I made in LR 3 ported over (color label, star rating, keywords, Develop enhancements) except the Flagging.

LR 3 w/Flags


LR 6 no Flags


How can I get the flags to sync?

I plan to purchase a laptop to take with me when I travel to shoot and want to be able to sync/import everything including flags. My likely scenario would be new photos on the laptop that are then moved to my PC. However, if I flag photos on my laptop, I want to be sure that that information ports over to my PC.

Thanks

"I did a simple test to see if the changes I made in LR3 would port over to LR6."

LR 6 will read and convert a LR 3 catalog, and in doing so will read all the flags. Does that not work for you?

"That's pretty huge if you are traveling away from home/office and you set flags for photos to review and reject and then synchronize the folder in LR6 and no flags port over in the sync."

LR provides other mechanisms that let you work on a laptop while travelling and then efficiently transfer that work to your main computer. In particular, you can use File > Export As Catalog and Import From Another Catalog.  See this Lightroom Queen article for details: 
https://www.lightroomqueen.com/how-to-lightroom-catalog-multiple-computers/

I'm not arguing against this feature request (I voted for it a long time ago) but rather pointing out that there are existing LR features that can accomplish what you want

I did a simple test to see if the changes I made in LR3 would port over to LR6. Everything ported over except the flags. That's pretty huge if you are traveling away from home/office and you set flags for photos to review and reject and then synchronize the folder in LR6 and no flags port over in the sync.  This is a huge feature in LR and should work.

There is an annoying bug in Lightroom. Flags (flagged, rejected) aren't saved to the XMP file. I worked months (countless hours) to flag the images, then I saved the metadata and removed the cr2's form catalog for backup. I sadly discovered that all flags has gone!

Adobe Bridge saves Rejected as XMP:Rating=-1
I wonder why Lightroom can't do the same?

Until Adobe gets it working for all smart objects regardless of content, my recommended workflow would be:
- Open up the file you want to use as a smart object
- Save As PSD/PSB
- Drag file onto main comp / use File > Place on main comp
- Keep your main comp at 1x resolution and use Export As for scaled output

By contrast, if you wrap an existing smart object within another smart object just to change its file type, you’re wasting more disk space than necessary. Nesting smart objects only makes sense if you’re planning on using their respective layers stack to transform multiple layers as a group, or apply smart filters to them.

So, for every external file we drop in as a smart layer, we need to scale it up, drop it in a layer folder, and make that layer folder a smart object, then position it in our design as required. Then when we use Generate settings on that smart layer, all will be well?
It's a great tip... but boy, what a hassle.

Apparently the feature DOES WORK as expected as long as your high-resolution raster smart objects are of PSD or PSB file type.

This explains your findings that smart objects created from layers worked, but placed files didn’t. Creating a smart object from a layer yields a PSB file, which works. By contrast, if you place some PNG/JPEG/TIFF/etc. via File > Place or drag-n-drop, the file type is preserved. And for smart objects of any type other than PSD/PSB the export feature ignores the embedded/linked content, and simply falls back to scaling the rasterized version as it is stored with the layer, thus producing useless blurry pixel-bloats.

This holds true for Photoshop CC 2015.5.