This was an issue introduced in 2018.2.17f1 and a fix is being investigated currently. As @sperepel pointed out, you can force your project to user 2018.2.16f1 rather than “latest 2018.2” and you shouldn’t run into this issue. Will keep you all updated on progress here.
Wanted to update everyone with another possible solution/workaround. We have narrowed down that this behaviour will only be exhibited if the Project contains UnityScript(Javascript) files. Removing these files or converting them to C# should alleviate this issue.
@ollieblanks Is there a way to search a project for UnityScript(Javascript) files? (I have more than 3,000 script files, a tiny portion of which might be javascript, from external assets).
EDIT: For others, a brute for approach, from file explorer, is simply to search for the .js file extension:
To the team: If you have known this issue for over a week, it’d have been nice to either disable 2018.2.17f1 for cloud builds, or at least show us a warning in the build page. I just wasted 2 hours looking into what could be wrong with my project before finding this.