BPA Object - AzureStorageUtility - List Blob Items - input is not a valid Base-64 string

[GoForGoldTech]

Hi
When executing BPA Object - AzureStorageUtility to List Blob Items, I get the following error message:
The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters.

I suspect it is a tilde (~) character in the access key string. The Account Name and Storage Container characters are all valid.
Can you advise how this can be resolved.
Thanks