When doing Get Latest, is there a checkbox called something like "Overwrite existing files"? Try ticking that, which should force the file to be downloaded. You might need to do it through VS12, rather than through RH as I haven't used RH with source control recently.
When you get the latest version through RoboHelp, do you not see the changes in RoboHelp or are you also not seeing the files on your local computer. Also, is there any difference when performing a get through RoboHelp or VS?
You may want to try deleting the CPD as that file can cause these sync problems.
It turns out that the .cpd file was the culprit for the glossary problem. Checking out the entire project before importing the glossary was also key.
For the missing images, even though it was a copy/paste over existing file names in Windows Explorer of just a few .png files, we discovered that you have to check out the entire folder in Visual Studio before pasting in the new images.
Thank you for those who responded.