[moved to hardware forum]
I am using CS6 an BM Multibridge also only for preview (no chaptue) outout via SDI oder HDMI to a professional Monitor Sony OLED 2541 (SDI or HDMI).
To use BM you need to open a own BM timeline which you can choose in CS6-Settings BM - properties. With standard CS6 timeline SDI output does not work.
You should now:
When you use effects in a CS6 standard timeline, somtimes rendering is not necessary (green line). When you use BM (in my case Multibride) + CS6 Effects/ColorCorrection (or RedGiant or others) rendering is VEVERY time necessary. If you dont use Effects/ColorCorrection rendering ist not necessary.
A proper NLE helps in this case very much.
Same for AE CS6.