CKEditor toolbar missing when conditional field becomes visible
Not finding a built-in way to avoid the problem of missing CKEditor toolbars on conditionally displayed fields, instead of using the Conditional Fields module, I use the Asset Injector module's JS Injector to inject this JavaScript into the node add/edit page (note that the authors field is an entity reference):

var el = document.getElementById("edit-field-authors-0-target-id");

if (el) {
  showHideBio();
  el.addEventListener("change", showHideBio);
}

function showHideBio()
{
  var el = document.getElementById("edit-field-bio-wrapper");

  if (this.value) {
    el.style.display = "block";
  }
  else {
    el.style.display = "none";
  }
}


Seems to work just fine, but open to suggestions for improvement. Thanks to @Taggart Jensen for the idea.