HomeKit stops propagating Item state to Home App

I’m running openHAB 4.3.1 via latest release of openHABian on RaspberryPi 4 and startet to experiment with HomeKit integration.
I created a new Item of type Switch and added Apple HomeKit Metadata Switchable.OnState.
The HomeKit bridge could be paired in Home App without any issues and my Switch-Item was discovered.
When toggling the Item state (ON/OFF) in Home App the state change event is received correctly in openHAB and I can see the correct state in UI. Unfortunately when toggling the Item state in openHAB-UI the event is not received by the Home App after some seconds.
It seems that the change can only be received for around 3 seconds after interaction with the Home App. After re-open the Home App the correct status is displayed again.
Is this a bug or do I miss something?

Running OpenHAB 4.2.0 still and iOS 18.2 with the “new” HomeKit architecture enabled (not sure if this is still an opt-in).

I can’t confirm this, all status changes done in OpenHAB UI are nearly instantaneously reflected in the HomeKit app, even if I don’t touch the HomeKit app for some time.

Either there was a change between 4.2.0 and 4.3.1 or something is different in your iOS or network setup.

Which version of iOS are you using? Do you have power save mode enabled? Do you still see the “update” for your home to the new architecture?

I updated iOS to the latest version 18.2.1.
There is no option to upgrade to new HomeKit architecture anymore.
I tried the same setup with openHAB 4.2.0 but no luck.
It seems to be an issue with my network config, but have no clue what is wrong.