Broken roll-up calculation when using hour durations for sub-tasks?

I have a parent task called Foo and two sub-tasks, Bar and Bie. When I enter 1h as the duration for both sub-tasks, the roll-up duration calculation for Foo shows 1.125d. I'm actually seeing this throughout my sheet with another instance having 4 sub-tasks add up to 5h but the parent shows 0.375d. I've made sure the length of day is set to 8 in the project settings. Any idea how I can get accurate parent task durations?

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