Homekit dimmer group problem

I have this Group:Dimmer:MAX item that groups three dimmers.

Group:Dimmer:MAX            gBalcony_Light_Ceiling                 "Deckenbeleuchtung [%d %%]"                     <light>             (gBalcony_Light)                                                 ["Control", "Light"]              {homekit="Lighting, Lighting.Brightness", alexa="Light" [name="LEDs am Balkon", description="LED Deckenbeleuchtung am Balkon"]}

The item works flawless in the openHAB Main UI and with Alexa. But it doesn’t work as I intended when using the homekit addon.
In the homekit app on my phone it shows the current value of the group, but as soon as i try to change the value there is an error in the openhab log and nothing happens.

[WARN ] [ristics.impl.base.BaseCharacteristic] - Error while setting JSON value 11 for characteristic io.github.hapjava.characteristics.impl.lightbulb.BrightnessCharacteristic

java.lang.ClassCastException: class org.openhab.core.items.GroupItem cannot be cast to class org.openhab.core.library.items.DimmerItem (org.openhab.core.items.GroupItem and org.openhab.core.library.items.DimmerItem are in unnamed module of loader org.eclipse.osgi.internal.loader.EquinoxClassLoader @324a50)

Since it works with Alexa and MainUI im not sure if it is a problem caused by me or a homekit bug. Any ieas?

yes, it looks like a homekit binding bug.
which version of openhab / homekit binding do you use?

openHAB 3.4.2 Release Build and 3.4.2 Version of the binding.

I can confirm this happens when sending commands to a group of lights. OpenHAB 4.1 Release.