Audio popping five seconds into video

Hello, sometimes when I finish rendering the video and watch it to see if everything seems okay, there would be an audio pop round a few seconds into the video, but the rest of the audio is fine. In the original source audio, there is no pop, the volume levels are fine (only just hitting the green area), and so on. I export the audio using AAC (the same as source audio), 320kbps, 48000 hz, which is exactly the same as my source audio. I have also tried making the first few seconds of the audio fade in, as apparently that can help, but I'm still encountering a random pop five seconds into the video. I'm guessing this is a bug, as my levels and everything else are fine.