I'm trying to make an NPC temporarily Blind, but have hit an issue-- during a GameMode Block "SetAV Blindness" (or ModAV) have no effect UNLESS I first edit their Blindness via the console... Does anyone have any suggestions to how to fix this, given that I cannot use the "Onload" like the BlindMoth Priests have (since it's a Vanilla NPC)?

Is it a magic effect or a quest script? That changes things.

Right now, an Object Script attached to a Token-- I tried a Spell effect Script, and got the same issue. Not tried a Quest Script yet.

Yep, tried it myself too - with no prevail. It is possible, that it has to be in an OnLoad block... I will still try once, making a quest that gives an NPC the blindness. Will report back in a minute.

EDIT: I got it to work, when I used a reference. That's possible it works only that way. Will test it further.

EDIT nr.2: So it would seem. I couldn't succesfully reference the NPC using a spell, and even with an token it didn't work. So, if it is just one NPC you want the blindness for, the easiest (and possibly the only working solution without OnLoad) is to give the NPC a reference name, and then use it in the script; be it an spell or an object - either way works.