I reviewed the examples you shared and noticed that ngSanitize and the ng-bind-html directive are used. It seems that the styles are stripped by that directive and there is not much we can do about it. Here
is an updated example that illustrates that the model contains the expected value, however it is displayed in a different manner depending on whether ng-model or ng-bind-html directives are used by the textarea element. The inability to select and style the bullet points is a known limitation, caused by the fact that the style should actually be applied on the block element (<ol> at this case), which is non-selectable. I am afraid there is no simple, user-friendly workaround that I can suggest at this point.