VB Studio Build failure

Summary:

Deploy job fails with "Error: Status of instance OICINST_BT-QA could not be determined at this time. Please try agin later or contact your system administrator for help."

How can I debug this?!

Content (required):

In Visual Builder Studio "Builds" section we have package and deploy jobs for our QA environment.

Since it was last used 2 months ago, the deployment job is now failing with error:

"Error: Status of instance OICINST_BT-QA could not be determined at this time. Please try agin later or contact your system administrator for help."

I've checked the QA instance status is "Available" within the Environments section.