XF 1.5 Tags and Google analytics giving soft 404

I'm getting lots of soft 404's in my google search console. All the URLs are /tags/ urls which as a member I can see. However google's bots can't and see a soft 404. (I can see this in the google fetch and preview).

Can anyone advise on how to prevent this? I have the default xenforo robots.txt which doesn't disallow the /tags/

thanks in advance