Sorry - I forgot to look at this.
The reason for the security stopping is that the device reports that it supports security command class version 0. This is interpreted by the binding as the command class is not supported, so the binding removes support for this command class (as per the ZWave specification).
This causes the binding to stop using security and I guess the device doesn’t like this. This is not new though - it’s been in the binding for many years.
I could guess that this was an error - ZWave error detection is quite poor, and given that the device has clearly initialised in the past, I assume that it did not always report version=0 or it would never work. I would therefore suggest to try and reinitialise - if it still returns version 0, then we can add a workaround in the binding.
Looking more at the time you reported that the colour command doesn’t work (18h42), it looks like it’s working fine -:
Here we see the binding send the colour command, and the binding acks this command. All is sent securely and I don’t really see any issue. There are a number of these colour commands sent around this time, and while I’ve not checked every single one, they do look like they are working ok (by which I mean the command looks ok, and the device acks the command).