Duration is incorrect and inconsistent within same sheet

What I'm trying to do:

Link "start date" and "duration" from Sheet A to Sheet B

What's happening:

I can link the cells just fine. But the duration is being calculated differently/incorrectly. Eg I have one row with a start date of 10/4 and a duration of 5 days. Based on the sheet settings, the end date should be 10/8 (which it is in Sheet A). Instead, the end date in Sheet B is 10/11, a full additional working day.

The holiday/working day settings are the same in both sheets.

Another thing I can't figure out is why this is happening inconsistently. In Sheet B, a task several rows above under the same parent has a duration of 1, and it is correctly showing the start and end dates as the same dates. But a few rows lower a task with a duration of 1 has an end date a day later than the start date.

Finally, the overall duration in the parent row is showing as a fraction?

Screenshot is of Sheet B. This shows ALL of the rows under the parent.