Same here,

I have created a storage credential,

I have created the external location. 

I can use COPY INTOto copy data from the external location,

I can use the Load data UI from Azure.

What I cannot do is use spark.read or db.fs.ls on the external location it will fail with "Invalid configuration value detected for fs.azure.account.key" 
I mean why do I need to set the properties if it works elsewhere, isnt that the point of creating the storage credential after all?