Thanks for the thorough explanation!!!
Unfortunately, I haven’t modified any audio object at any time. Would you think that piece code is out of place and could cause this assertion to fail? Otherwise, I’m afraid it’s some engine code doing the mischief 
if (AudioComponent)
{
FAudioDevice *AudioDevice = AudioComponent->GetAudioDevice();
if (AudioDevice)
{
FActiveSound *ActiveSound = AudioDevice->FindActiveSound(AudioComponent->GetAudioComponentID());
if (ActiveSound)
{
Percent = ActiveSound->PlaybackTime / AudioComponent->Sound->GetDuration();
}
}
}