Our team is stumped with this Fmod bug in 4.15+. When we use multiple Fmod ambiance Loops in 4.14 in a scene we get no delay on the loop.
When we do the same in 4.15 and now using 4.16 recent Fmod updated plugin and master build. We get a delay on sounds looping over.
If we only place one ambience into a scene the loop for it plays fine. The more we add to the scene the greater the loops delay becomes. We are using a streaming dynamic level setup. But issue persists in testing scenes.
To be clear even tho Fmod loops are perfectly fine and have been for many builds of unreal ever since updating to 4.15. Multiple sound sources in a scene cause a loop delay.