A few days ago i started a new game and noticed that there was no cinnabar in all the redstone veins. I tried several worlds. 6.14.15 version.
Then i downloaded 6.14.01 and cinnabar was there. I changed these versions several times and the result was the same.
I have GT and some mods like NEI, waila etc. Every time i changed versions and tried a new world i reinstalled minecraft. Is it a bug or maybe i missed something in changelogs?
Are you sure it is the same Redstone Veins as the ones you talk about? I did add a Redstone Vein that is basically only Redstone, quite a while ago.
With this fact i continued searching and finally found cinnabar in one of redstone veins. Thank you!
Using a Cauldron to wash crushed Redstone Ore can give you Cinnabar as Byproduct, that might help.