I've built a custom interface on a SharePoint Form (list-bound custom edit form created from SharePoint Designer) that relies on a block of code loaded in a Simple Form WebPart (javascript and CSS) to restyle and extend the functionality of the page. This was needed mainly because our SharePoint instance is hosted, and therefore we couldn't just knock together the correct form in Visual Studio.
For most users (I believe all users in the past) the form loads correctly, including the JavaScript and CSS, but it turned out that our users in one region weren't getting it. Looking at the HTML of the form that they were getting, there was no evidence of the webpart there at all, which led me to think it was a permissions issue of some kind - and sure enough, when I added All Site Users to the Target Audience section of the WebPart, for most people it showed up.
For some, it still doesn't. I've even tried adding groups that I know they're a member of (iterated the groups using the CSOM on their user object from their machine, so guaranteed they're there). Nothing. Can anyone give me any idea why this is happening and how to fix?