@Kah Wei Are you referring to migration guide mentioned here? AFAIK, moving a DI resource from one subscription to another will not move the underlying storage account data, this data should also be moved to the new subscription separately and configured to use the same with your new projects. Since you have mentioned that the old storage account was working fine for few days, did you create a new project in the new subscription and resource and configure to use the old storage account? If yes, then is the storage account still available in your old account?
I would recommend moving the data in your old storage account to a new storage account in the new subscription for easy access and then configure them to use in your projects. If you have already moved your previous trained models to a new storage account in this subscription use the same storage account to move the data too.
I hope this helps!!
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