WFO: Exact vs Simulated: Wildly Different?

1. For data, I used EURUSD 1H in Test Precision: “Selected Time Frame only”
2. I created Walk-Forward Matrix using Simulated method. Then I pick the best Runs/Pct setting. 
3. Then I run WFO with that Runs/Pct setting in both Simulated and Exact methods.

 

In Simulated, WFO result is better than original unoptimized strategy, as expected.

But in Exact method, WFO result is a lot worse than original unoptimized strategy.

 

Why is WFO result so different between Simulated and Exact methods?

Should I use data in Test Precision 1 minute to avoid this discrepancy?

 

Hello,

 

simulated mode is an approximation to the exact. So the exact method should be more predicative. Can you also attach the strategy file or send to [email protected] so I can test it?