My bosses dumped MODx on me, a Java and Web Developer. No MODx experience. And no: there is no support, documentation, or MODx go-to guy.
I tested the most basic change: editing a Chunk to add a simple HTML comment. I have been a Web Developer for years, And used Joomla, Drupal. So I know proper HTML syntax for comments and everything else. However, the test comment I add in the editor inside MODx manager for a given Chunk does not get deployed to the actual site. Nor to the View shown upon View Button. Even w. browser cache clear.
In the MODx Manager, I DO check the checkbox for "Clear Cache on Save".
Is this normal behavior or is something broken? What step am I missing? WHy dont even my test comments I add show up on the page? I have confirmed that the Chunk HTML IS on the page. Just not my change. Meaning: I am sure I am editing the right chunk for this page.
Try the Manage -> Clear Cache menu item. Not knowing how your site is configured, it's hard to know if there is a custom cache manager controlling what gets cached, and what gets cleared when saving anything.
If you haven't already, try a simple plain text comment (e.g., testing) to rule out mod_security. You might also try deleting all files in the core/cache directory.
Have you checked the database to see if the changes appear there (modx_site_htmlsnippets table)?
What version of MODX are you using?