I have a project have this issue.
The Choose the devices that this bot will test with: dialog shows:
Test With: None (gray-ed out)
This server cannot build for any of the platforms supported by
this schema. Available server platforms: OS X, watchOS.
It can be built on server machine with the copy of Xcode using by Xcode Server and runs well on the simulators and iDevices plugged on that server, I have tested.
The Xcode Server itself works well, I have other projects with bots running on it.
It seems there is something wrong in the schema, but I have no clue so far. Any idea is appriciated.