I have a pair of glitches on my version of Leveled.
The first is that when I level up, it flashes the graphic that I leveled up but the stats in the corner don't pop up to show what changed. This is purely graphical, because comparing the stats before and after has them go up, but it is weird because it didn't do this at first. It started mid-session on a regular server (hosted by a friend) and at some point it wasn't showing the stats on a level up, and it has continued despite changing to the most recent version and a whole redownload.
The second one is a bigger issue. Upon beating a boss (be it single player, multiplayer, and the two version I played) there seems to be about a 50/50 chance that it won't drop any loot and any events that would normally happen as a result don't spawn, but I can still get experience and level up. For example, I killed the Wall of Flesh once, and when I beat it no loot spawned, the blocks that hold the loot didn't spawn, and hardmode didn't activate. The weird part is, when playing on my friend's multiplayer server and the glitch happens, it comes paired with a train of other weird visual glitches, such as the message counting who did what damage not including me (but the damage is split as if I had done damage, minus actually showing my name), the game sort of freezing as if lag is happening for an extended period of time, and the previous bug where loot didn't drop.
I haven't tested it to see if it only ever does this when you kill a boss and level up on it because that's kind of hard to replicate, but it is still weird.