I plug in TS cables in 1,2,3 and 4 no problem at all. Levels are fine. I plug them in 5,6 and 7,8. In stereo setting Left is less loud than R. In mono same. I pan the L to the Left and I pan R to Right but it's completely not centered. Seems to be sort of centered when I pan R in the middle.
Interface has latest Frimware and I'm running the latest version of UC.