Hey @RGJ
I could not reproduce your issue with a regular tag but I got the error you mentioned with a tag group
This is my sample CSV:
ABC,TAGGROUP
ABC works fine, but with the tag_group, it would error. If you could share a sample CSV, I’m more than happy to help!
I’ve made a PR fixing the tag group issue. Also, is SiteSetting.force_lowercase_tags enabled in your forum?