Issue Summary

Creating an x-axis annotation for a date must match the start of the "group" for the date bucket. If they do not, then the annotation is pinned to the left side of the x-axis instead of in the appropriate date bucket. 

Annotation using the "Start" of a bucket:

Annotation using the a date within the date bucket:

Here is a quick walkthrough illustrating the behavior as well:

https://www.loom.com/share/9a99e7e894a041dd83a125bf17470e15

Steps to Reproduce

1. Add an x-axis annotation to a chart that is grouped by date
2. Select a date for the annotation that is not the "start" of that bucket (i.e. mid-week if grouping by week). 

Expected Results

The annotation is displayed in the matching bucket.

Actual Results

The annotation is displayed at the left of the x-axis. 

Workaround

Select a date at the start of the range you want the annotation.