I found the reason. The process “quasar” does not use the proxy settings from the .npmrc file, it uses the environment variable “http_proxy” (I have only checked it under Windows). The syntax corresponds to the syntax of the .npmrc file.
One thing I have noticed though, is if you are missing the colon (:) completely, you get a warning and it keeps on trucking (instead of failing), but it gives you a message about no descripter so won’t be used. For the line number it gives you, look up 1 higher for the issue.