Adding inline styles to TinyMCE in Plone 5.1/5.2/style not selectable

I configured an inline style "Visual" within the TinyMCE controlpanel however the style is not selectable (its disabled) from the format menu!? Anything missing here?

I found this:

Anyway...this is a bug..configuring the same thing twice makes no sense.

I use this:

{
  "style_formats" : [{
      "title" : "MyVisualInlineStyleClass",
      "inline" : "span",
      "attributes" : {
          "class": "visual-a"
      }
  },
  {
      "title" : "MyVisualBlockStyleClass",
      "block" : "p",
      "attributes" : {
          "class": "visual-b"
      }
  }],
  "style_formats_merge": "True"
}

in the TinyMCE Config, Section "Other Settings"