We’ve just uploaded 18.104.22.168. It has changes to how Content Security Policy (CSP) works.
A CSP is required for PhoneGap apps. If you do not supply one, AppStudio will fill in a very loose and insecure policy. You will need to define a better one and put it in Project Properties, in the PhoneGap section. Read this to learn more about Content Security Policies: https://developers.google.com/web/fundamentals/security/csp/
Web Apps do not currently need a CSP. However, if you would like to define one, put it in the extraheaders property.
Please give 6.3.05 a try and see if this works for you!