Just to put your mind at ease, our brand see's a similar CTR but I have put below some considerations.
- With Google Privacy settings and the emergence of "None" it might be possible that Google registers the impression but counts the click as "none" - very unlikely.
- Do you run paid adverts on your brand? Is it possible people could be clicking these? Factor this in when considering the overall CTR.
- You said Google Maps is on the right - if your brand is a restaurant /venue/shop it's possible they click that result and go to Google Maps, and still find what they are looking for.
- Is your brand name unique - if other companies have it, people may see the results and decide thats not what they are looking for?
- Could your brand name be confused with other products?
- Are other people bidding on your brand name.
- Is your Meta Descritpion fully optimised? This is basically a written advert for your site. Is it as optimised as can be? Is there a call to action.
I'll think of more but lots to think about.