Ok, I get it now. That is pretty likely considering that Kingdom Hearts disappeared in the aftermath of the Keyblade War, i.e. when friends turned on each other to gain more light. Then again, the Foretellers did set out to collect more Lux in the first place to reach Kingdom Hearts so that they might meet the Master again, hopefully. So it almost seems like it’s set up that nobody in the χ timeline actually knows what it is either and consequently end up driving it out completely by losing sight of the connections that are really important.