I experience the same problems. All new projects don't have the Sandbox option. I tried the "AppCloud Default Project" using BM 5.15.0 and also used the "Blank" project and inported the "AppCloudServices" module and configured my App correctly. In all circumstances the option "Run in Sandbox" is unavailable. Also in the Dev Portal, go to Project, there is no technical contact mentioned. Is there some how a relation between both ?
The option 'Run in Sandbox' is available for Team Server enabled projects, only. Are your projects Team Server enabled projects (available in 'Open Project' -> Team Server Project drop down list).
You could test this by creating a new project based on the "AppCloud Default Project", with the default settings. I tested this and the "Run in Sandbox" option is enabled in my test project.
Same problem here (5.13.1). I opened the project with the Team Server drop down list but the Sandbox is greyed out. How can I solve this?
Problem solved. I have justed been told that as soon as an application is connected to a Cloud Node the sandbox option is disabled.