filtering the_content

I wrote a very simple plugin (text filter using preg_replace) that is supposed to work on ‘the_content’ using ‘add_filter’. It’s essentially not much different than one of the examples from the codex (it’s super simple). There shouldn’t be any pluggable functions issues or the_excerpt issues as far as I can tell.

The plugin function works perfectly if I place it directly in the loop, feed it $post->post_content, and echo the output. It works perfectly on the admin Edit Post page in the Post Preview section at the bottom of the page.

It does NOT work in the loop when using the_content().

I cannot figure this out.

I’m working with version 1.5.1.2