Hello, I have recently joined a sevtech server with a few friends and i invited them to my together forever 'party' this is good but only i can complete the advancements.
If the players of the team were offline when the trigger for a sync happen, that sync will occur when they join to the server. It will not let anyone else complete them. It’s probably the most significant update we’ve made in Minecraft’s recent history - we’re releasing a new version of the game that lets players on Xbox, mobile, VR and Windows 10 play together! The big day is finally here! Although the sky is the only thing that is white not other things on the surface. Ok I started a hardcore world and I played on it for a few hours then I quit, then when I hop into the world again, its all just white.

By default Advancement Syncing and GameStages Syncing is enabled. Together Forever is a Team API that allows you to sync stuff like advancements or gamestages between the players of your team. Together Forever.