Resolved at 1:50PM UTC: Our support teams have worked with Talos developers, who have deemed this benign. This has been rectified by changing the file disposition in AMP, which effectively allows our customers to access the file. This update should be reflected on our customers' appliances in the next 1-2 hours.
We are currently investigating reports of two specific files, possibly tied to Office365 updates, being either categorised as Malicious retrospectively or actively being blocked.
We are still clarifying whether this is a false positive with our internal teams.
As the investigation continues, we will provide further updates.