SPEAKING OF MULTIPLAYER BUGS WOWIE here's a biggun.
So, on this dedicated server I'm running, my partner was using the Drillinator to do some world-saving from the fresh-spawned corruption in Hardmode, and well...
I was on the opposite end of the world, at the beach, about to cut some trees, when SUDDENLY everything started breaking but not dropping anything.
I figured out it was the area around my cursor with my Smart Cursor on, even though I only had a hamaxe equipped.
Turns out, blocks were breaking for me, when she was drilling. This also caused massive desync because the blocks drilled fine for her.
See: Aftermath, my POV:
Her POV:
(Don't mind the loot, King Slime randomly spawned between screenshots)
Also video of a test we did to confirm this behaviour:
Edit: Upon re-opening the server, every block that didn't break for BOTH of us has reverted to its pre-breakage state.