I can't see anyone's score in-game.

Some add-ons can conflict with the Raider.IO add-on and may hide the data. Try these steps to track down what is going on:

1. Disable all add-ons except Raider.IO. Do tooltips now show? If so, then another addon is conflicting with the Raider.IO addon.
   
2. Check your Raider.IO addon settings to ensure that tooltips aren’t disabled, and that modules for your character’s faction are enabled. (You can type /rio to open Raider.IO Addon Settings)
3. Are you running an up to date version of the addon? Try to Raider.IO Desktop Client to make sure you always have the latest data.