Thanks for your proposed fix to the problems that I encountered. The issue seems to be closely related to the href bug raised in Oct 2018 in that the code renders correctly in the dashboard editing window but will not save upon exit from this window. Then some of the HTML characters disappear from the text editing window when the dashboard is opened a 2nd time.
Unfortunately, I am unfamiliar with GitHub. A first impression of the subject just undertaken is of a confusing, impenetrable jungle of jargon that will take me some considerable time to grasp. I need to find a GitHub for Dummies before going further!
Your screen shots of the two HTML lines I used for illustration appear to have rendered and saved correctly but I have to leave it to others to try out this pull request to verify your fix.
I have come to a standstill having initialised a git repository in my pi/home area and have no desire to corrupt my working system by any making further stab-in-the-dark changes!