When a latest version is updated manually, e.g. correcting data in an Item Details field, the data propagates to the working version of the item.
When a latest version is updated via import, e.g. after a new field is added to Item Details, the data does not propagate to the working version of the item.
This creates a problem when that data is required for subsequent versions, as in the example above, the field remains blank for the next version.
I have had a support case (17988978) where this was confirmed as expected system behaviour. I am convinced that our tenant previously updated working versions when imports were applied to latest revisions, perhaps this was a useful bug.