Unable to add home location to airtag

I bought an AirTag. I frequently leave it at home and each time I get a notification “the item is left behind”. I try adding a “notify me, except at” location but each time I get “unable to add location. There was an error adding this location”. What can I do about it? I have many other airTags that work well with this location. The problem is only with that specific airTag. I've tried restarting the airTag already. IPhone has latest update installed. Other functions of airTag work well.