I've finally got it solved and working (I'll go and double-check in a second - just saved and came here to reply in my immediate joy at being given the option to speak to Hildiran at all!).

Mine started working only after completing "Taken For Granted" way after completing the main story arc (current power level 477). Is Taken For Granted a pre-requisite to start?! Because if so, that needs far better signposting!

@ubi-froggard As above, still having the problem on 1.5.0 on PC.

Quest marker missing and she's still at her altar and can't be spoken to.

Sadly, it doesn't appear fixed with the new update - at least not with me.

Have updated, loaded, saved, restarted and the old woman will still not be talked to! Bit frustrating now.

For reference, running on PC.