Each non-nested event in an FMOD Studio project has a corresponding input bus. Each input bus acts like a group bus, receiving input from every instance of the corresponding event and creating a mix that becomes its output. When you assign an event to a VCA, you’re actually assigning its corresponding group bus to that VCA - and that’s why the post-fader sends and effects on your events’ master tracks aren’t affected by the VCAs to which those events are assigned: Effectively, the VCA is controlling the fader of the hidden bus that the events are routed into.
If you want an event’s post-fader master bus effects to be affected by a VCA, we recommend moving them to the group bus into which the event is routed, and assigning that group bus to the VCA instead.
Originally, we intended input buses to function as an additional signal chain and mix between the event instances and the group buses of the mixer, but we later discovered that the vast majority of FMOD Studio users preferred not to use them. We therefore decided to optimize them out.
We couldn’t simply remove them immediately, however. They were (and still are) an essential part of how the mixer functions under-the-hood. Instead, we committed to gradually phasing them out, beginning by hiding them and making them less accessible in the UI. This is why they’re not longer visible in the mixer.
Eventually, they will be removed entirely. In the mean time, there are only two ways to interact with an input bus: By assigning it to a VCA, and by using FMOD Studio scripts to edit its signal chain.