Try to ask advice at the Stack Overflow forum site. That website is more suitable for questions about web development.

• http://stackoverflow.com/questions/
• https://support.mozilla.org/en-US/kb/where-go-developer-support

Clearing the cache from the settings menu makes the changes show up in the debugger on the next refresh. It is tedious to clear the cache every time I make a change, so I have disabled caching in about:config, but that slows down browsing everywhere, all the time. It would be nice to have the option to disable local cache while the developer toolbox is open, but I suppose that this has turned into more of a feature request than a question, so I will try a different forum.

There is a checkbox in the toolbox settings to disable the HTTP cache when the toolbox is open.

• https://developer.mozilla.org/en/Tools/Tools_Toolbox#Settings

As stated in my original post, the problem persists with that option enabled. Furthermore, the response from the server contains the updated code, so the caching must be happening locally. I've found an open request in Bugzilla and added what information I can to it: https://bugzilla.mozilla.org/show_bug.cgi?id=1363534

FF can't change codes AFAIK. So did you contact the IT department to ask them what is going on as well?

I am a part of the small IT department at our company. In the screenshots attached to my original post, you can see that the Firefox debugger is displaying different code than it received. Firefox executes the new code received from the server as expected, but I cannot set breakpoints on any new code that I add if it is not displayed in the debugger.