Solved
Numbers for the same month don't match in Analysis Workspace
When I create a 13-month report, why does the same month have different numbers? This occurs for all metrics:
UVs:

Referrer Instances:

Occurences:

When I create a 13-month report, why does the same month have different numbers? This occurs for all metrics:
UVs:

Referrer Instances:

Occurences:

It looks like you're using a visit-based segment, which will impact both metrics you're comparing.
Since we're talking about something like a 0.0003% variance, It probably isn't something you need to worry about.
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