The HLOD layer deletion method was created out of desperation and trial and error with a bit of luck. With one project I’ve done it 17 times to be able to publish updates.
Build Landscape from the menu up top of editor, that has Build HLODs.
Is more of a map checker and not the actual building of the landscape, I think it should have a different name, but it checks for a few things and will let you know if there are some problems, like spatially loaded actors attached to non-spatially loaded actors etc
It does give thousands of Yellow Warnings for all props about Static mesh actor has NULL static mesh properties, these can be ignored.
There is a show filter to see only the Red Errors.
The Red Errors need to be fixed and if underlined double clicking on them usually will select the prop thats the problem.
Check-in Changes and making snapshots with Unreal Revision Control may be sufficient and more reliable than making a copy, as you can sync back to an old snapshot if things go wrong and have your project how it was when the snapshot was made.