Shelly S4SW-001P8EU (1PM Mini Gen 4) — device stops responding to commands over Zigbee after Shelly firmware 2.0.0

What happened?

After the Shelly device firmware was updated to 2.0.0 (Zigbee variant, app = Mini1PMG4ZB), the device pairs and is visible in Zigbee2MQTT, publishes its definition correctly, but no longer executes any command sent over Zigbee. Every state set (ON/OFF/TOGGLE) fails with an APS-level timeout — the relay does not switch, and no acknowledgement (APS ACK / ZCL Default Response) comes back from the device.

The same behaviour is reproducible on 8 identical units, all of which worked correctly before firmware 2.0.0. The device firmware update is the only change; the Zigbee network, coordinator, and Z2M version were unchanged at the time the problem started.

The device remains fully reachable over WiFi/RPC in parallel (Shelly.GetDeviceInfo, Switch.Toggle, etc. all work), so the hardware and relay are fine — only the Zigbee command path is affected.

What did you expect to happen?

Publishing {"state": "ON"} (or OFF/TOGGLE) to zigbee2mqtt/FRIENDLY_NAME/set should toggle the relay and return the new state, as it did on the pre-2.0.0 firmware.

How to reproduce it (minimal and precise)

Shelly 1PM Mini Gen4 (S4SW-001P8EU) running device firmware 2.0.0 in Zigbee mode.
Pair it with Zigbee2MQTT (interview completes, device is recognised as Shelly S4SW-001P8EU).
Publish {"state": "TOGGLE"} to zigbee2mqtt//set.
Observe: relay does not actuate; Z2M logs a genOnOff command timeout after 10000 ms (see log below).

Zigbee2MQTT version

2.12.1

Adapter firmware version

0xc02cedfffecb9551 Révision: 9.0.1 [GA]

Adapter

SLZB-06M

Setup

Home Assistant on Proxmox

Device database.db entry

No response

Debug log

log.log

The device I tested the more is 0x7c2c67fffe6dbfec (known has shelly_wc_bas before being deleted and reintegrated)

Notes

No response

Start by reproducing the failure with the Shelly S4SW-001P8EU on firmware 2.0.0, Zigbee2MQTT 2.12.1, and the listed SLZB-06M adapter, then inspect the linked debug log and the genOnOff timeout. Done means ON, OFF, and TOGGLE commands published to the device set topic actuate the relay and return the expected state without an APS timeout.