Groups assignment not saving on Tags

Hi,

I’ve installed the Tag Groups plugin fine and followed the “First Steps” instructions to set “Tags” as the Taxonomy to use and have then successfully set up two groups.

Now if I go to the Tags page and click on either Edit or Quick Edit on a tag, the dropdown is there to assign the tag to one of the Groups I’ve set up. However, if I choose and group and save the tag, it still shows as Unassigned in the main Tags list. If I go to re-edit the tag, it also shows as unassigned there too.

The same happens when trying to either create a new tag and assign it to a group or use the Bulk tools to assign the tags as well.

Any ideas?

Thanks in advance,
Steve