The difference between 1.15878 and 1.1548 is 40 pips, pretty large number.
Do you know how this block works? Because it reads the trades, calculates their average lot size and average open price using some formula (imagine that the result is one single position) and sets SL of all trades to a particular level behind that invisible "open price". Of course, each trade is still individual, each one still have its type (Buy or Sell) and depending on the current price you are able to set SL at certain level for some of the trdes, but not for others.
Imagine you have Sell trade that is on profit. You can't put the SL level below the current price.
Imagine you have Buy trade that is on loss. You can't put the SL level above the current price.
When you have mix of Sells and Buys, it depends, some of them might be out of the game.