Transitioning from Lantus to Tresiba

Need some help here. I’m having weird issues, and I am not sure if this is because of Tresiba. Here’s a screenshot of what I mean:

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Since I was seeing weird behavior, I did a test. I injected 0.8 units of Humalog (I prepared fast acting carbs to keep the BG from dropping too low). As you can see, the BG decrease started as expected. But then, suddenly, there’s this weird peak. It dropped back to 87 mg/dL … and has remained there so far. And notice that it has only been ~1 hour after injection, so the insulin is still active. And yet, the BG does not drop!

What the hell? What is wrong here? This completely destroys any usefulness bolusing might have. Any suggestions? Could this be Tresiba dosages not being large enough? Or perhaps stress hormones (I did not get much sleep)?

EDIT: I figure that this question would fit better over here.