Hi nAth,
Intensity Shuttle is a bit difficult to get working 100%. It requires very specific USB 3.0 chipsets. I believe the only one that is OFFICIALLY supported is the NEC/Renesas chipset. Many claim to have gotten it to work with some Intel chipsets, but I've never gotten mine to work with anything BUT NEC/Renesas. Even so, I got constant BSODs. BMIS is a nightmare.
Anyway, as for the audio stutter on OBS, the only way I got it to work was using Decklink. Always stuttered using WMD, no matter what I did. The workaround I came up with was to buy an RCA -> 3.5mm jack and I connected the audio output from the BMIS to the input on my sound card and I used the sound card as the audio source.
Hopefully someone with better luck will have a better response for you.
Good luck!
- EDIT -
Have to admit, though, that I haven't tried/bothered using my BMIS in a LONG time now. I completely gave up on it as I wasted FAR too much time on trying to get it to work properly, without success.