Okay, this is dirty, but works with a little work. at the right of each group and the addressbook are three dots. click that for each and create a csv export. Then, merge all of them into a single spreadsheet. Sort by primary email address and the ones that are single will be the unassigned ones. I'm writing this quickly, and maybe a pivot table would do the work for you in identifying the unassigned.

You mean that contacts in groups will have more than one record in the composite file? and those who are groupless will have only one?

That would mean I'd have to combine the CSV from the entire address book + a CSV from each group (not just combine all the groups).

That sounds right. And if there's no other answer, you'll get the thumbs-up.

I think it would also be wise to create another column to key each batch with the name of the group. I can imagine wanting to see that info (at least sometimes).

Since this is likely a 1500- to 2000-record spreadsheet, and I'm a bit pressed for time, I'll just wait and see if any other ideas turn up.

Dirty as it is, I do appreciate your thoughts, and if nothing else turns up, I will try it.

I"m sorta' brain-dead today, but I think a pivot table might separate them - but I would have to put my head in a bucket of cold water to rediscover my knowledge of pivot tables. However, if interested, here is a link that may help you in this: https://exceljet.net/pivot-tables/pivot-table-show-duplicates