Shelly Dimmer 2 set brightness doesnt work

Hello,
since a while I am using a Shelly Dimmer 2 via MQTT.

I added now a Shelly bypass and did a FW update of the Shelly. After that, the setbrightness doent work anymore.

When I am doing this:

MQTTShelly2DSchlafzimmer_.sendCommand(ON)

MQTTShelly2DSchlafzimmerBrightness_.sendCommand(50)

MQTTShelly2DSchlafzimmer_.sendCommand(OFF)

The light turns on with the preused brightness of 10, turns off again. When the light is off and I try to set the brightness only, the light turns on to 10.
So in principal the setup to the Shelly seems correct, but the setbrightness doesnt work as expected.

Do you have something similar?

Thanks and BR
Tonias