Homematic - Last Packet Received not working

Hi community,
I am using OH 2.2 stable release and it’s working well for me with Homematic and homegear. I’ve added the “LAST_PACKET_RECEIVED” Datapoint to my Items file but it seems that the item is not able to pull a proper value.

This is the item line:

Number Dimmer_Bedroom_Lamp_LastPacketReceived   "Schlafzimmer Stehlampe letztes Paket [%d]"                     <siren>         (gBedroom,gLastPacketReceived)          { channel="homematic:HG-HM-LC-Dim1T-Pl-3:homegear:XXXXXXX:0#LAST_PACKET_RECEIVED" }

From karaf console:

openhab> smarthome:items list | grep Dimmer_Bedroom_Lamp_LastPacketReceived
Dimmer_Bedroom_Lamp_LastPacketReceived (Type=NumberItem, State=0, Label=Schlafzimmer Stehlampe letztes Paket, Category=siren, Groups=[gBedroom, gLastPacketReceived])

From homegear cli:

(Peer)> config print
        Channel: 0
                [LAST_PACKET_RECEIVED]: 5a 6e 18 a9

I know that is a hex value, in dec it is ‭1517164713‬ as epoch timestamp

root@raspberrypi:/# date -d @1517164713
Sun Jan 28 19:38:33 CET 2018

Does anybody have this working properly?