About the Softlock thing - did you have Piggy Bank? That causes an easy infinite against enemies with Greed. I should probably do something about that because it literally locks you out of fighting the Leprechaun
Buffs do expire at the start, but I'm not sure if that's aligned with the player's expectation so might change it
Bosses don't add an extra item, it's probably the "start with free item" thing triggering when it shouldn't