MacOS – Text substitution does not work with Slack on Yosemite

it sounds like someone has deleted your shortcuts or hit a restore defaults button.

I recommend that you

• setup time machine to save your preferences each hour. then you can use it to restore your preferences. that should help you identify the problem.
• setup a shortcut that you will use daily (maybe ⌥, to pull up system preferences)

hope that helps regards

The substitutions for Pages.app are stored in: ~/Library/Preferences/com.apple.iWork.Pages.plist

Specifically they are in Root/kSFWPAutoSubstitutionArrayProperty. The format is a an array containing dictionaries with the keys replace, with and on.

The Global Substitutions are located at ~/Library/Preferences/.GlobalPreferences.plist. Specifically, they are in Root/NSUserReplacementItems. The format, conveniently, is identical.

It's probably possible just to open ~/Library/Preferences/.GlobalPreferences.plist as plain text and copy across what you want into ~/Library/Preferences/com.apple.iWork.Pages.plist.