Hello Raj,
Welcome to the Microsoft Q&A and thank you for posting your questions here.
I understand that you would like to know what caused the issue you are having when you disable public network access for an Azure Storage Account, it should block incoming requests from the internet by default but not.
Understand that disabling public network access restricts external requests, but private endpoints and proper authorization mechanisms still allow controlled access to your storage account. https://learn.microsoft.com/en-us/azure/storage/common/storage-network-security
To block all public access to Azure Storage Accounts: https://harvestingclouds.com/post/block-all-public-access-to-azure-storage-accounts-via-manual-setting/
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I hope this is helpful! Do not hesitate to let me know if you have any other questions.
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Best Regards,
Sina Salam