I was doing buster quests today and after I destroyed the castle and poping the crystal, the game said that I got drops for such and such, but there were no drops on the floor for me to pick up. I restarted the game and the same thing happened again.

then you must have been playing free match as it doesnt give anything other than buster medals. free matches gives you buff to your lootings on main matchs for 2 times when you do 1 free match an it stacks 2 times to have total of 4 main match buffed lootings.

if its not that then not sure why