What is the output of running uname –a and iotkit-agent --version?
Have you tried to restart the agent before setting the new attribute?
systemctl stop iotkit-agent
systemctl start iotkit-agent
Using the website, are you setting the attribute by going to Devices > + Attributes > Edit Attributes > New_Attribute > Confirm Attribues > Save ?
I am not using the iotkit-agent or admin for this project, but connecting to the mqtt broker directly. However, this should have nothing to do with either of those as this is just about updating the metadata within the backend about the device (unless the iotkit-agent is somehow updating the metadata itself...).
I am trying to use that process you mentioned via the dashboard, and neither it nor updating the device via the REST interface lasts.
Now Im thinking the iotkit-agent is updating the metadata; does it do that and can I get it to stop (without disabling it, though I could as I dont use it anyway....)