Q: I'm trying to view the Sacred Vessel to know what my target is, but the symbol is not shown:
A: The issue can be fixed by going to Options > Display > Effect Intensity and configuring the setting back to the default '100' value. If you are using a low-end PC and worried about performance, you can dial down the setting to around '50' and still faintly see the symbol.
Q: My target kills are not being counted towards the quest.
A: The targets you defeat are only counted if you have the Sands of Inaros quest set as your active quest, you kill the targets yourself, and with the 'Sacred Vessel' equipped to your gears.
If you don't meet all of the conditions above, your kill will not be counted towards the quest.