Channels of Homematic things do not get updated


I have the issue, that Switch-Channels don’t get updated, if the Switch was not changed via openhab.

I can switch via openhab just fine, it gets sent to homematic correctly, but if I change the state on the device itself or via homematic webinterface, it takes a long time until it gets updated in openhab, or sometimes it doesn’t happen at all.

I would have expected, that the state gets updated via this rpc callback? I have set the Callback IPs in the bridge - can I somehow check in Homematic if it was registered correctly? How is this supposed to work?