Move terms from one taxonomy to another keeping the hierarchy

I am creating a custom taxonomy for the first time. I am trying to add a Location taxonomy. What I am actually trying to do is use existing categories to make them into locations.

I went into the database table wp_term_taxonomy and manually changed the taxonomy column of the ones I wanted from category to location.
This seemed to work pretty well, posts are assigned to the desired locations and everything seems to be fine, until I go to the Locations page in the admin interface and find myself with an empty list, even though it detects the existing locations and lists them:


If I manually add a new Location through the interface it appears on the list correctly.

What could be causing this?

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