At complete random, sounds can often have a loud "pop" added to the end when exported. This happens incredibly frequently especially when exporting multiple sounds at once. Some sounds will have this happen almost every time when played, others won't.
This issue is easy to replicate on shorter sounds such as those for Fortnite weapons. See FortniteGame/Plugins/GameFeatures/CherrySmokeWeaponGameplay/Content/Gameplay/Pistol/Sounds/Pistol_CherrySmoke_Drop_01.uasset as an example.
GitHub refuses to let me upload a video for some reason (and when downloading files, gives me a 1kb file instead, thanks). Will attach a demonstration if need be whenever that resolves itself.