Spam Events Reappear on Calendar

Spam calendar events keep reappearing on an iPhone despite purging the source .ics emails from the user’s Exchange Online mailbox.

Details:

• The spam events originally came from .ics attachments sent to a distribution list (info@...) that the user is a member of.
• The user’s mailbox was searched using Microsoft Purview; four matching items were found and purged using New-ComplianceSearchAction -Purge -PurgeType HardDelete.
• The purge completed successfully with Item count: 4, Failed count: 0, and Status: Completed.
  Despite this, the same 4 emails reappear in subsequent compliance searches.
• The mailbox has no litigation hold, retention hold, or in-place hold enabled.
• The recurring spam events continue to show up on the iPhone calendar after deletion. 
  

Why do the messages still appear in content search after a successful purge, and how do I fully remove the associated calendar events from the iPhone? Any help here would be greatly appreciated!