Legacy Of The Vaal

So im on my second character in act 3 havent hit cruel yet. I joined a friend in progress because he needed help. He was at the part in the quest where you have to put soul cores in the statues. Not knowing he was much more ahead of me. I cannot actiate the stone altar myself beacuse i was not on that quest step. I signed out and signed back in, i even switched servers but for some reason i cannot progress further. Nor can i go back to the quest step i was on well before that.

I need some help and any is much helpful.