So I looked into the issue and found a weird Type Error occurred when I was dragging the above node from the palette to the editor area on Node-RED v0.20.6.
TypeError: undefined is not an object (evaluating '$("#"+e.target.id).offset().left')
The weird thing is the error was never thrown when I use the node from GitHub version of Node-RED v0.20.6. The NPM version of NR caused the error.
You can reproduce it with node-red-contrib-lwm2m node, which I developed.
How can I resolve it?
And, according to the user report, v0.20.5 did work fine without any errors so something changed in v0.20.6, I guess but don't have any idea of the resolution after reading the release note.