Tried to add Border Styles to the image plugin in the TinyMCE in CMS as per Episerver Customizing the TinyMCE editor guide.

I have added the image plugin and enabled image_advtab as per TinyMCE image plugin guide. And when clicked on the image plugin at CMS, it has an advanced tab.

However, when I clicked on the Border Styles in the advanced tab, there are no items in the list/dropdown. How can I add items to the Border Style list ? I have tried the below and it does not work.

public void ConfigureContainer(ServiceConfigurationContext context){

context.Services.Configure(config =>
 {config.Default()
                        .ContentCss("/Templates/RelatePlus/css/editor.css")
                        .AddPlugin("image")
                        .Toolbar("image")
                        .AddSetting("image_advtab", true)
                        .StyleFormats(
                    new { title = "Bold text", inline = "strong" , selector = "img" },
                    new { title = "Red text", inline = "span", selector = "img", styles = new { color = "#ff0000" } },
                    new { title = "Red header", block = "h1", selector = "img", styles = new { color = "#ff0000" } });

});}

Here is the screenshot of the dialog box. (Clicking on the Border Style will not provide any items as a dropdown) --> https://1drv.ms/u/s!Ao3_PEzak8vNlTnS-uxrFZ7cvzb9

Note: I am working on CMS ---> 11.5.1.0

(I could not upload an image to this question because, even in this Episerver forum's TinyMCE image upload not works. It has no place to upload or select a file other than typing the source after clicking on the image icon. Screenshot --> https://1drv.ms/u/s!Ao3_PEzak8vNlThleoJia5q_ZCXV )