Negative peak detector hits "minimum" value
Input common mode range is the problem: -


The signal input voltage range for an LT1057 starts from about 3.5 volts above the lowest supply voltage. If your lowest supply voltage is -5 volts, then all bets are off if the input is lower than -1.5 volts
The output voltage swing may get to within 2 volts of the negative rail.


These are typical figures only. I'd look for a different device or increase the supply voltage levels.