This usually means that the track has been mixed loud and that dynamic plugins that are typically used during the mastering process may have been used on the master output of the mix.
Peak headroom is crucial for mastering because LANDR uses the space you leave to apply all of its mastering treatments. LANDR can’t do all that much for your mix if it has no room to work.
Don’t add any dynamic plugins like limiters and compressors to your master channel for the sake of loudness. LANDR will take care of that for you. You can definitely have plugins on your master bus, just not ones that are there for intensity/loudness reasons.
Check out more details here.
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