Custom taxonomy not importing correctly

I am trying to import records into a custom post type with with a custom non-hierarchical taxonomy (US States). I have separate each value with a comma, and selected the appropriate taxonomy in the mapping section. It imports them, but entries with multiple values are not imported as individual tags, but rather a lump of words separated by commas all as a single tag, like this:

“Alabama,Alaska,California,Florida,Georgia,Louisiana,Mississippi,Nebraska,Nevada,New Mexico,New York,North Dakota,Oregon,Washington,Canada”

As a test, I imported the same file as a built-in WP post and tags (not custom). They imported correctly this time, as individual tags, like this:

Alabama
Alaska
California
etc

Any idea why the regular tags are working properly, but not the custom tags? And will this same problem occur with custom categories?

Thanks,
Celeste

https://wordpress.org/plugins/wp-ultimate-csv-importer/