When you use the item_used_on_block trigger in advancements, it does'nt trigger for all items: 
Here the advancement for flint_and_steel and the reward function:
flint_and_steel.json flint_and_steel.mcfunction
This totally work as intented, the player who click on a cobblestone say the message in chat, but with diamond_sword it does'nt work :
diamond_sword.json diamond_sword.mcfunction
 
Here the datapack that i'm using for the report : report.zip