The name of the lantern particle wasn’t renamed to “iron_lantern” along with the block. The following command is not accepted:
/particle block{block_state: {Name: iron_lantern, Properties: {hanging: false}}} ~0 ~4 ~0 0.25 0 0.25 1 1
However, this command is:
/particle block{block_state: {Name: lantern, Properties: {hanging: false}}} ~0 ~4 ~0 0.25 0 0.25 1 1
Sorry, I thought lantern was also renamed, not just chain. Please close this, since I can’t (can I?)