Symptoms
You receive the following message on your Mac:
"Microsoft Defender ATP" Would Like to Filter Network Content
All network activity on this Mac may be filtered or monitored.
Cause
Microsoft Defender contains networking features to protect your Mac from connecting to malicious websites. However, you may need to manually allow the feature before it will work as designed.
Resolution
Click Allow.
OUTCOME
You will no longer receive the prompt and Microsoft Defender will function as intended.