I have been looking into this problem a bit more this afternoon, and after running your code, my backtest is showing to me that trades are happening as expected at 3:46PM on full days and 12:46pm on half days. Those are time-zone adjusted to my browser. I'd expect you to see the same times, but offset for your timezone.
However, my colleague ran your code as well and got some trades being made at 4:46PM. At this point, we are not really sure why this is happening but we are in the process of investigating it! I will let you know when we figure it out.
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