[KNX2] [SOLVED] None of the configured GAs on channel could handle the command

I did some more tests on this and found out that channels with additional listening GA didn’t work. I configured two Things exactly the same way besides the listening GA:

Thing device neu3 "Neu3" {
    Type number : testmeout "SendNumber" [ ga="6.010:9/5/3" ]
}
Thing device neu4 "Neu4" {
    Type number : testmemore "SendNumb"  [ ga="6.010:9/5/3+6.010:9/6/3" ]

And two items:

Number sendTest "Test [%d]" { channel="knx:device:bridge:neu3:testmeout" }
Number sendTest2 "Test2 [%d]" { channel="knx:device:bridge:neu4:testmemore" }

If I use sendTest with my rule it works. If I use sendTest2 it doesn’t. Here are the traces:

2018-06-09 12:50:58.701 [TRACE] [.internal.handler.DeviceThingHandler] - Handling command '0' for channel 'knx:device:bridge:neu3:testmeout'
2018-06-09 12:50:58.704 [DEBUG] [nx.internal.client.AbstractKNXClient] - Wrote value '0' to datapoint 'command DP 9/5/3 'knx:ip:bridge', DPT id 6.010, low priority' (0. attempt).

2018-06-09 12:57:06.879 [TRACE] [.internal.handler.DeviceThingHandler] - Handling command '0' for channel 'knx:device:bridge:neu4:testmemore'
2018-06-09 12:57:06.888 [DEBUG] [.internal.handler.DeviceThingHandler] - None of the configured GAs on channel 'knx:device:bridge:neu4:testmemore' could handle the command '0' of type 'DecimalType'

Any hints are welcome on how to continue on this.

PS: I had to create a lot of new things for testing as changing channel configuration was not applied at runtime. But I think there is a bug open for this already. E.g. changing DPT doesn’t have any effect - the previous DPT will still be used.