# Layered snapshot bug: one layer's preset Program Change hijacks another layer's sound (cause + fix)

**URL:** <https://discourse.zynthian.org/t/layered-snapshot-bug-one-layers-preset-program-change-hijacks-another-layers-sound-cause-fix/13336>\
**Category:** Using Zynthian\
**Created:** [June 29, 2026, 2:26pm UTC](https://discourse.zynthian.org/t/layered-snapshot-bug-one-layers-preset-program-change-hijacks-another-layers-sound-cause-fix/13336 "2026-06-29T14:26:18Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![smatheus](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/smatheus/32/16436_2.png) [@smatheus](https://discourse.zynthian.org/u/smatheus)\
**Post date:** [June 29, 2026, 2:26pm UTC](https://discourse.zynthian.org/t/layered-snapshot-bug-one-layers-preset-program-change-hijacks-another-layers-sound-cause-fix/13336/1 "2026-06-29T14:26:18Z")

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Sharing a tricky one I just chased down on my Pi 5 / V5, in case it helps anyone running layered setups.

Setup: A 4-layer snapshot, all chains on the same MIDI channel so my keyboard plays them together:

- JE8086 (JP-8000) – “Tiny bells”
- LinuxSampler – Salamander Grand
- Pianoteq
- FluidSynth – an “FM Piano” SF2

One of these is my own modified/improved JE8086 integration that loads both individual panel patches and Performances spanning both panels — full write-up + preset bundles here: [https://github.com/smatheusale/zynthian-custom/blob/main/JE8086.md](https://github.com/smatheusale/zynthian-custom/blob/main/JE8086.md)

Symptom: After loading the snapshot, the FluidSynth layer played violin/strings even though the screen correctly said “FM Piano”. Re-selecting the preset by hand fixed it — until the next snapshot load.

Cause: The JE8086 layer selects patches via MIDI Bank Select + Program Change (Tiny bells = bank [0,1], PC 40). That PC was being sent on the MIDI channel, so every chain on that channel received it — including FluidSynth. FM Piano.sf2 has no bank 1, so FluidSynth fell back to the GM soundfont, where program 40 = Violin. FluidSynth’s own channels output gave it away:

Instrument not found on channel 0 [bank=1 prog=40], substituted [bank=0 prog=40]  
chan 0 … preset 40, Violin

A second issue: loading a snapshot didn’t re-trigger the engines’ set\_preset, so they started on their default patch despite the right name showing.

Fix: Send the preset Bank Select + PC through the chain’s own zmop (zmop\_send\_program\_change / zmop\_send\_ccontrol\_change) instead of a global channel send — that confines it to the originating chain. Plus re-fire set\_preset after restore for engines that load their patch there. Both layers now restore perfectly, and manual preset changes still work.

Filed upstream: [Layered snapshot: a chain's preset Program Change leaks to layer-mates on the same MIDI channel (and restore doesn't re-fire set\_preset) · Issue #1705 · zynthian/zynthian-issue-tracking · GitHub](https://github.com/zynthian/zynthian-issue-tracking/issues/1705)

Hope it saves someone the headache! 🎹