@chris Is it possible that your latest changes prevent Tradfri bulbs from going OFFLINE altogether, or at least for a very long time?
I have a rule that updates item state when a Tradfri bulb goes offline, basically to detect if mains power has been turned off and reflect the correct state in the UI. It seems this doesn’t work anymore.
Anything is possible 
Ca you provide a debug log please and I’ll take a look. It shouldn’t do this - what the changes do is to poll a device if it doesn’t report in after its reporting period rather than immediately setting it offline. This does a kind of “last check” to see if the device is really there or not before it’s marked offline.
Of course it’s possible something in there isn’t working as I planned though 
I have hopefully found the issue. The last chance timer is meant to be set to 30 seconds - the timer was being initialised in seconds, but I’m used to defining things in milliseconds, so it was 30000 seconds. If you can wait 8 hours, it should work (hopefully!) 
I’ll create a fix for this later today.
Edit: I’ve created the PR and started the build…