Homematic IP Sensor not available anymore

Hello all,
I hope you can help me.
After I registered a Homematic IP temperature sensor from one CCU to another CCU for better reception, this sensor is no longer available in HA.
Deleting the orphaned sensor in HA and restarting the CCU and HA did not help.
Can you give me a tip on how to get the temperature sensor back into HA.

thanks a lot
Mirko