Hi Troy!
It sounds to me like you are referring to AutoCAD Tool Palettes? Could you please confirm? And when you say the .atc file is not updating, do you mean to say that you close AutoCAD, open it back up and the new block is gone from your local tool palette? Or just that the file timestamp on windows has not changed? Do you have multiple tool palette file locations?
I will be able to help you more once I have those answers. Configuring tool palettes to work over the network is complicated; you're definitely not alone in your struggles. I had a ton of trouble setting my company up.
With the information you provided, it sounds like the tool palette may be saved in a location different than you think; Especially if you are duel-wielding tool palette catalogs, as is the ideal solution for networked tool palettes. It's also possible you're mistaking the catalog file, for the palette files, but from what you've written, I suspect you would know the difference.
Here is a link to a fantastic resource on tool palettes. This is a handout from a presentation at Autodesk University about CAD standards, and using standard tool palettes across multiple machines. I believe that PDF originally taught me a lot of what I know about tool palettes.
Best wishes!