Is your sound a 1-shot sound and is thus starting to play outside the max radius of your attenuation? 1-shot sounds will automatically cull if out of range and you’ll never hear it. If you want the 1-shot sound to persist even if out of range (and thus come in range when you walk within the radius), you’ll need to check “bVirtualizeWhenSilent” option for the sound wave. This will tell the audio engine to play it even if its out of range.
Hundreds and hundreds of sounds try to play so we use this max-distance cull as a reasonable optimization for most cases so we can avoid decoding and rendering audio that we won’t hear.