I noticed a bug in version 0.8a :
When you recover your stamina (sleeping/respawning) your strength turns "NaN".
Waking up usually restores this. However not always. One example is the "Deserted Base" location. After jumping down, if you loose a battle there and respawn your strength is perpetually "NaN" causing your attacks to do 0 damage. this does not happen in the base game.