I'm finding your same issue and I can't be specific I find myself looking at settings and pushing it back to stereo.
We bought new Bose solo. We have a sony flatscreen but had to use the optical cord hooked from bose solo to cable box. It would not work hooked up bose solo to tv. Talked with Bose tech and we had to change some speaker and audio settings on TV. Then sound from solo worked well. Just today I tried my dvd player and I can not get sound from DVD. Also bought bose universal remote but still can not get sound from DVD being played. Please help.