Strange AJAX issue

Ok, I have a strange issue with an ajax-ed page for my plugin. It was working fine for weeks now, then all of the sudden, I activated it on one of my sites, it worked fine for a while, then just stopped. The console is logging that it can’t find an ajax page in my plugin directory. I haven’t changed anything with the plugin code-wise. I tried to bring the ajax page up in a browser and it brings up a 404 page. I’m not 100% sure what the issue is here, but it appears as though a setting somewhere got changed. There are other people who work here that can make changes. Has anyone ever had this issue before? I can’t for the life of me fathom what has changed. Any advice is appreciated!