I know there is this item you need to get, Ancient Tablets, and people even started receiving multiple of them. Is that why they were removed from the loot pool? I can’t get one to complete the quest.
Also can someone explain how crucible works? Does the second crucible opens if I get the stone tablet? I saw videos on Youtube where they went into a different crucible with chests hidden all over the level. Has that changed?
I am not sure what the video u are referring to is showing, but i am pretty sure its the loot room after the boss.
in the crucible you basically go from room to room while picking up buffs/perks on the way. In the middle there is a vendor where u can use the unique currency from killing enemies inside the crucible to unlock new things.
at the end there is a boss. if you are done with the boss and got your loot u can do it again. as it is rogue-lite it will be different for each run. different perks, different map order etc.
and what stone tablet do you mean? you get a quest in sacrament to talk to someone to open the crucible. not sure what it is called i am bad with names 
but i am sure someone will pitch in and help out.
thanks for pitching in, i knew i could count on the community to clarify what i missed 