Long-form instrumental collapse into radio/station-surfing montage + hallucinated lyrics (~10–20s)

[Decentricity]

Summary

When generating a 2-minute fully instrumental cyberpunk cue (strict no-vocals / no-drums / no-bass), MiniMax Music 3 starts coherently for roughly the first 10–20 seconds, then collapses into what sounds like a broken radio / station-surfing montage: abrupt genre/timbre cuts as if switching broadcast stations, compressed “over the air” texture, and hallucinated vocals/lyrics despite an empty instrumental lyrics track and an explicit no-vocals caption.

This reproduced on two independent seeds with the same prompt.

Environment

• Model: MiniMax Music 3 (ComfyUI INT8 path: minimax_music3_dit_int8_convrot + pruned INT8 text encoder + DAV)
• Backend: local ComfyUI (EmptyMiniMaxMusic3LatentAudio + MiniMaxMusic3TextEncode + KSampler + VAEDecodeAudioTiled)
• GPU: NVIDIA GeForce RTX 4070 Ti (12 GB)
• Target duration: 120 s
• Seeds that failed the same way: 101, 202
• Output duration observed: ~120 s each

Prompt (exact)

Lyrics

[instrumental]

Caption

Global Metadata
Genre: instrumental synthwave / cyberpunk film score. BPM: 92. Key: D minor. Neon-noir, cinematic, epic undertones — like a Blade Runner rooftop climax or a rain-soaked chase resolve. Slow-burn grandeur without turning into a pop song.
Application: a two-minute cyberpunk movie cue: melancholic, heroic, and widescreen.

Vocal Details
STRICTLY NO VOCALS. No singing, no speech, no choir, no hummed melody, no vocoder voice. Fully instrumental.

Arrangement
ONLY these three sound sources, throughout the entire piece:
1) Electric guitar — clean-to-slightly-driven leads and atmospheric chords, cinematic and expressive.
2) Saxophone — smoky, lyrical cyberpunk noir lines; occasional heroic long tones.
3) Gamelan — metallophone / gong / bronze-bar textures and interlocking patterns, used as the harmonic and rhythmic sparkle (not as drums).

ABSOLUTELY NO DRUMS of any kind (no kick, snare, hi-hat, percussion kit, electronic beats, trap hats, industrial hits).
ABSOLUTELY NO BASS of any kind (no bass guitar, no synth bass, no sub bass, no 808).
No pads-as-orchestra beds that replace the trio; keep the mix as guitar + saxophone + gamelan only. Let guitar and sax carry melody; let gamelan provide shimmering rhythmic pulse and epic metallic resonance. Build intensity through harmony, register, and density — never through drums or bass.

Observed failure mode

1. 0–~15s: mostly on-brief — instrumental cyberpunk / noir cinematic texture consistent with guitar/sax/gamelan intent.
2. After ~10–20s: structure breaks. The track starts behaving like channel surfing: sudden jumps between unrelated musical fragments, as if flipping between radio stations.
3. Vocals appear anyway (spoken/sung fragments / lyric-like content) despite [instrumental] + strong no-vocals constraints.
4. Arrangement contract (only guitar + sax + gamelan; no drums/bass) is largely abandoned after the collapse.

This does not sound like ordinary mild long-form drift (instrument fading / emotion softening). It sounds specifically like a broadcast montage / radio continuity prior that the global model falls into once the initial plan loses grip.

Notes / hypothesis

Official docs already say section tags and descriptions are not strict symbolic guarantees (tempo/key/instrumentation/lyrics/structure may mismatch). Separately, the Music 3.0 blog discusses long-form brief-drift as a problem Music 3 aims to mitigate.

I could not find documentation of this specific radio/station-surfing + lyric hallucination failure mode. Happy to provide short audio excerpts from the two failing takes if useful.

Ask

• Is this a known failure mode (e.g. radio/broadcast material in training / long-context mode collapse)?
• Any recommended mitigations for multi-minute strict instrumental generations (caption structure, section tags, CFG, shorter chunking, etc.)?
• If this is unexpected on the INT8 Comfy path, is there a preferred reference config to re-test against?

Thanks!