The achievements "Uneasy Alliance" and "Feels Like Home" only unlock when in the default minecraft:overworld. New worlds created with the Bukkit API don't unlock the advancements despite being an overworld dimension, which conflicts with other advancements like "Subspace Bubble", "We Need To Go Deeper" and "The End?" which all unlock in worlds that are not the default Overworld, Nether or End respectively.

This makes it impossible to unlock all advancements on a server that uses the Overworld as a lobby world.