I use the same path in other actions without problem.
I found out that in the latest version of CI (188.8.131.528) the double-quotes are not needed in the working directory.
But I encounter another problem now. When I click Save & Continue or Save & Exit the wizard, I get the following errors
Can you send us a diagnostics report (either via private message here or to support @ finalbuilder.com) - you can find the diagnostics report on the admin eventlog page of Continua CI. Make sure you generate a fresh report before downloading it. This will allow us to figure out what build eventhandlers you have and what settings etc.