I'm not sure what could be causing that at the moment. Would you mind filling out a second level support request for me? You can find the form here:

https://www.interactivetools.com/support/email_support_form.php

I'll take a closer look at how you have the system set up, and see if I can find the issue.

Thanks!

Greg

I've done that and uploaded it but nothing (there are things in the dropdown but are showing as blank lines). See attached screengrab.
When I take down the wysiwyg_custon.php file now nothing is displayed in the dropdown.

Any suggestions?

I don't think you need to create a file called wysiwyg_custom.php.  If you want to add custom CSS to your WYSIWYG editor, you need to create a CSS file called wysiwyg_custom.css in your lib directory:

cmsAdmin/lib/wysiwyg_custom.css

Any CSS rules you add to this will be used in your WYSIWYG editor. 

Thanks!

Greg

I'm trying to add new CSS styles into the wysiwyg_custom.css file as in the archived post but I can't seem to get any of these new styles to appear in my editor.

Could someone let me know what I'm doing wrong? I adjusted the wysiwyg_custom.php file so that the new styles were in the following: 
theme_advanced_blockformats : "p,address,pre,h1,h2,h3,h4,h5,h6,p-dotted,capt,subtitle,quote",

But when I then view the wysiwyg editor it just shows blank lines in the dropdown and I cannot style the content as needed.

The files are under here: http://www.twentyfifty.co.uk/cmsAdmin/(etc)