It seems that because of the new zodiak buffs, it was your intention to reset buff assignment to zodiaks for all characters during maintenance for 10.6.1.1005 patch? (I.e. allow players choose the buff for every zodiak again)
It worked most of the time but not for all characters. My best guess is: if a character had more than 1 zodiak summon stone of the same type (say, 241523), say, one in IS backpack, one in partner backpack, then using it now still simply gives the previously assigned buff, the assignment was not reset automatically.
Does not matter that much imo, but still: maybe you could fix this automatically next time? Or players could ask for reset scroll if this is the case for their toon?