'The name staxo-faqtags is already in use'

I’m getting the error message ‘The name staxo-faqtags is already in use’ in each line when trying to add my custom taxonomy ‘faqtags’ as a column.

I’ve tried using a different theme and disabling all of the plugins except one: ‘Custom Content Types Management’ which actually creates the custom post type the tags are attached to. The error message remains.

I’m using the ‘Admin Columns’ plugin on another site, which uses the same theme and many of the same plugins. There I don’t have the problem.

Is there an obvious area you could suggest I look at?

https://wordpress.org/plugins/codepress-admin-columns/