Yeah… for some reason I had the same issues with compiling on 6.1, used comfychairs “howto: Use Atmel AVR Studio 5.1 to make a .hex file” and now they all compile like a champ!
I had to download the version from his link though…not sure why it doesn’t work on 6.1 but works fine on 5.1
I have a shared repository of the STAR firmware and a few custom builds as well