Invalid Analytics Report ID exception from a valid report ID

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I'm trying to fetch an Analytics Report using the sample code provided.

However I'm getting an invalid ID exception, I've triple checked the ID is valid and accurate, and tried to fetch other reports via ID with the same error. 

I'm wondering if this is a SOAP issue, the docs say get() is used for Primary Objects, however the Primary Objects list doesn't include AnalyticsReport. This is happening on a v14.11 site.