Microsoft has now released a fix for their recent issue with transparent labels. It is now safe to enable Office updates and install the latest Office update.
To enable updates:
Click File and then Account
Click the Update Options drop-down and then click Enable Updates.
You may get a notice pop up asking if you 'want to allow this app to males changes to your device?', choose Yes
Click the Update Options and then click Update Now.
Now simply wait for Excel to download and install the updates.