Occasionally, shift key functions, such as proportionate element scaling and content scaling stop working in InDesign CC. I don't know what causes it, and so far the only solution I've found is to restart my machine. Does anyone know the cause or a better solution? We've spoken with support and they had us reset our preferences in the cloud, which didn't work.
It can be caused by third-party software grabbing keystrokes. Some have reported it's related to using a particular web browser so you could try another.
You could also try creating a separate user on your computer. If it works, it could because of some corruption in your system.
We activated the Root User and that worked, and repairing disk permissions also seems to have worked. Thanks for your input!