I have checked the manual notes on the code completion and can't find anything that would indicate why the Feather Tooltips would stop working. Feather tooltips and candidates would normally appear while typing in a function name, etc. For whatever reason, mine have stopped working. I have disabled and reenabled tooltips, uninstalled and reinstalled (and cleared the Game Maker data...
Feather Tooltips No Longer Displaying
Feather Tooltips No Longer Displaying