On my History website using the Fresh theme with "United", the buttons are a solid colour and don't show the text except for the search box. Using the same theme on my other site Oil Group the buttons show text. Is this a bug?
I just had a look and the buttons seem to be working fine for me. Maybe try a no-cache reload of the site. Ctrl-F5 is common for most browsers to do this.
Or try a different browser, to check to see if it's a problem with the site or just with a cached version.
Or, maybe I don't quite understand what the problem is. If it persists you could send a screenshot to email@example.com showing the problem.