I have the latest firmware and I can adjust the settings on inputs 3/4. But there is no “bypass mode”. I have old keyboard with the only analog output (yes, I know it is unpractical in VST times but I still like some voices). Sound in 3/4 inputs of UR28M is affected by AD/DA converter or preamp or maybe something else. I turned off all effects, changed hardware configuration in mixer. Maybe it is not a distortion, but sound is not as pure as in 2TR in.
It is not a big problem, but I still wonder why 2TR in does not flow signal to the computer…