We haven't gotten any other reports about the buttons to add Resources not working in any of the recent versions of in5. There was a report about 2.5 years ago where installing 3.7.3 seemed to fix it. You might try uninstalling in5 and reinstalling it.
Are you running any sort of antivirus? We've seen that affect users' ability to download updates via in5 > Info and Updates... or Scrolling Frames via in5 > Interactive Widgets > Scrolling Frames.
I haven't seen that behavior. If you notice the buttons not working with particular InDesign files, it may be that those files have become corrupt. You could try saving them as an IDML file and back as an INDD file: