All of the icons in TT Simulator are blurred (see image below)

TTSim2.jpg

I am running in Windows 10 64 bit in Steam.
I am running an AMD HD5970 OC with the latest supported AMD drivers. It's an older card, but still runs everything else in my library.
I am running at 2560x1600 resolution in full screen. The problems persist whatever the resolution though.

I have created a profile in Radeon Settings and tried every different setting with the same result.

I have tried recreating the game cache in Steam, same result.

On my 8 year old iMac, the icons display without a problem (albeit the game is unplayable because the iMac is so old!).

Any ideas?