The meta value was `+`-joined ("recordings+releasegroups+compress"). Sent over
the wire the literal `+` percent-encodes to %2B, which AcoustID does NOT split
into flags — so every hit came back with an empty `recordings` array and the
parser produced zero candidates (a fingerprint match that resolved to nothing).
AcoustID wants the flags space-separated. Verified against real fingerprints:
`+`-joined → 0 recordings; space-joined → 28, resolving Highway to Hell and
Living After Midnight to their canonical studio albums as the top hit.
ChrisBeWithYou
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