Another Bug, it's alluded to in the guys thread called 'TH10'. He says the thing builder is stuck on th9. This is an EXTREMELY annoying bug. He saw the drop down and he knows you can change it, but it's like the website doesn't recognize it has been changed in the dropdown, so all of the available buildings are the th9 buildings.
I always manage to get past it but I don't know how. I end up spamming clicks on it, or hiting tab then enter repeatedly really fast, or open the drop down with a click and then select it with arrows, or ninja around with the other drop down and then click on the townhall level drop down while the second dropdown is still open. None of these actually work when taken on their own, but eventually it switches over somehow.
Really flippin' annoying because I can't figure it out. I'm on chrome, on a mac. But Safari ninjas even worse.
EDIT: By ninjaing worse, I mean that safari lets me change th levels at will, but the drop downs for each respective building type (army, resource, other, etc.) are stuck after placing a building unless you 'scroll' or 'zoom' in the builder itself. This is a big annoyance when using it, because you constantly have to zoom in and out, and one little zoom, zooms it all the way in or all the way out.
Chrome works really well, except for the fact its nigh impossible to switch townhall levels.