Solved. My ignorance.

Discovered that the Edit Mode needed to be disabled. Can't edit the topic heading here, but should this be left, so others can read the solution?

Fixed in v2.4.0

An option to access the devtools is added to the context menu of the webpage widget in the version 2.4.0.

Fixed in v2.4.0. Please give it a try.

@andrep Open To-Do List settings, uncheck the "When Item Completed > Move It To Bottom" option and try again.