I have found that two build platform settings (Desktop, Mobile) in FMOD Studio having the exact same settings (Stereo, Vorbis 37%) make different outputs.
The banks built with Desktop setting are bigger in file size and they have better quality on iOS devices.
What is the difference between Desktop and Mobile settings?
It’s possible that your individual audio assets have platform-specific encoding settings that override the default per-platform settings specified in the Properties window. Have you at any time specified custom encoding settings for individual files in the Assets Browser? If so, be aware that these settings are platform-specific, and should be duplicated for the other platforms if you want them to be consistent.