CSV Import Custom Metadata Fields

Hi! I'm new to LT, and am in the progress of making some edits to existing spreadsheets so that I can bulk import my already catalogued books. I used the provided sample spreadsheet to get started, but am curious if LT supports custom metadata fields? I want to add a column like "origin" or "where from" so that I can track the bookstores I've been to. I tested doing this and neither the field or its data transferred. Any tips?

You must use the sample just as it is.

From Where field is among those that can be edited with power edit, so you might be able to quickly fill them later. You'll need some way to search and separate those you want to add the same data to, so I'd probably add that as a tag. Unless there's very many of them, you'll be finished in no time and can delete those tags in the process