PowerBi - Datetime value loses 1 second when changing the field type from DateTime to Text

Question

I have a DateTime value called "Hour". It represents each hour (rounded) of the day.

Due to other transformations I want to apply, I need to change the field's type to Text.

However, when I add a step to change the type to Text, the datetime value loses 1 second. This is wreaking havoc with my visualizations.

• 23:00:00 becomes 22:59:59
• 22:00:00 becomes 21:59:59
• etc.

Why does this happen? How can I prevent this? I've tried recreating all the steps from afresh but get the same result.

One odd thing I've noticed is that this issue tends to come and go with time, without me making any changes to the dashboard. One day it's there, and another day all the time fields end with 00. The underlying data source for the dates is a static Excel document and the data in the document seems fine and unrelated to the problem.

**Before: **

**After: **