Not showing in Advanced Forum Style dropdown menu.

Probably you use a too new version of Advanced Forum.
I have been neglegting the module too much recently and did not do updates to newer Versions (ashamed). Will do so later in the year.

Promise to take care after Nov 15. Am absorbed in D7UX, UX freeze keeps us running...

Cannot reproduce this. As long as you are using the 1.x branch with the 1.x branch of Advanced Forum, it works.
Maybe you tried the 1.x of Advanced Forum more Styles with Advanced Forum 2.x?

I am having the same thing happen with Advanced Forum 1.x. Nothing shows up.

dougbutner hm. Did you definitely switch advanced_forum_more_styles on?
I have not checked the latest 1.x version, so there might be some change the module does not reflect.
Going to /admin/build/themes and saving clears the theme cache. Going to the modules page and saving clears most of the others.

How do you install this if you are using advanced forums 6.x-2.x-dev?

Well you don's as it does not support advanced forum 2.x yet. Shame on me but that's the situation.

As Michele mention here, below is the code to port this module to be compatible with AF 2.x

function advanced_forum_more_styles_ctools_plugin_directory($module, $plugin) {
  if ($module == 'advanced_forum') {
    return 'styles';
  }
}

Well there is quite some more stuff to do to make it AF 2.x compatible, since the Templates have changed quite a bit and I do reuse the ones of the module mostly, so CSS needs to be partly rewritten.
It did it once but was thrown when trying to create a branch on Drupal CVS...

Anybody who experiences this issue and has the correct version of AdvFor_more_styles with his AdvF version, clear caches, then the style turns up in the dropdown.

For all others:
http://drupal.org/node/563136#comment-3147070

#8 worked :-)