Hello @Anonymous ,
I just tried the exact same template mentioned at https://learn.microsoft.com/en-us/azure/azure-monitor/essentials/resource-manager-diagnostic-settings#diagnostic-setting-for-azure-storage.
and it went through successfully.
Please find the attached template & Parameters file
[199767-enablestoragediag.txt]
Command used:
az group deployment create -g resourcegroupname --template-file .\enablestoragediag.json --parameters .\parameters.json