Thanks for running that test and sharing the UE Output Log screenshot, that’s very helpful.
From the screenshot it looks like FMOD is reporting a missing DSP plug-in (e.g. AudioWind). In that situation, the bank can fail to load correctly, and any events that reference the missing DSP may play as silence.
Have you tried to contact sales@fmod.com? They can advise on whether a plugin is available commercially and, if so, how it is purchased.
Sorry for the confusion here. FMOD Studio ships with a small number of trial plug-ins to allow evaluation in the tool. However, those do not imply guaranteed runtime support in any specific engine/platform without obtaining the appropriate licensed plug-in binaries from the vendor.
Also, we generally can’t remove them from Studio installers lightly, because there are existing users and shipped projects that may still rely on those plugins, and removing them could break backwards compatibility when opening older Studio projects.
As far as I know, there aren’t many actively maintained FMOD plugins that provide fully procedural audio generation in the way you’re describing.
If you’re open to an advanced option, FMOD supports writing custom DSP plugins via the DSP Plug-in API Guide.
There’s also a community thread with practical notes and Unreal-related discussion here: Creating a custom plugin