Did you try wrapping your operation in a single loop UI.timer as in the previous post to yours ?
Secondly, I think there are issues with #load_from_url, #load and #place_component with regard to operations.
We discussed some of this previous … In this post there is link to the official issue tracker where we discuss issues with some methods that break undo operations, …
Cancel multiple methods with a single undo in SketchUp - #2 by DanRathbun
… and also in which I posted a link to rigmarole tool clone here …