Alarm doesn't work anymore


Jul 29, 2019
I own and use for 6 months now a kit "smart home" xiaomi including a gateway V2 and 7 devices connected to it (2 motion detectors, 3 detectors doors, 1 temperature sensor and 1 switch). I mainly use this kit to secure the house (alarm).
Until the last weekend no worries to declare, everything worked ...

But now, the alarm is no longer triggering ! While the detectors are working properly.

Some precisions :
- I am version 5.5.45 in miHome
- I am connected on China server
- I use the automatic function "alarm" of the gateway
- I do not have other automations (no duplication)
- devices triggering the alert are well selected
- a reset has been made
- To test I have temporarily created a notification scene of motion detection. I go ahead, I receive the notification of movement but the alarm (in ON mode) does not trigger so no audible alarm, no visual alarm or even notification)

Do you have any ideas ?
In vain i searched in various discussion of this forum ...

Thank you in advance