I believe, starting with 2018.2 (and TSM), server configuration settings are no longer included in the backup. Therefore, every backup/restore is --no-config. The server configuration settings can be exported separately using the TSM settings export command. The settings, including your run-as password, are stored in a plain-text file in JSON format. There are instructions on how to perform the export, and encrypt it, at the following link:
See section titled "Import and export configuration information"
Hope this helps,