The domain xxx.virtual-venue.io may have been been categorized as a "Newly Seen Domain." More information on this category can be found here:
This is a time-based category which means the domain will become accessible after 48-72 hours if no malicious activities were found. Cisco Umbrella users can choose to block newly seen domains. If they do, Cisco Umbrella will block every newly seen domain for a period of time. This is an opt-in feature which is disabled by default.
If the "Newly Seen Domain" category is active, you should deactivate it or add the domain to the "Allow List" for the respective guideline so that the domain will be accessible and won't be categorized as newly seen.