Hello, I know that the post was created for a long time, but I had the same problem and I was able to fix it.
The problem (error C1083:Cannot open compiler generated file ‘….dep.json’: No such file or directory) occurs because the remote worker is trying to open a file that does not exist. In short, it caused by next MSVC compile arguments: /sourceDependencies and /experimental:log
How to fix: add the arguments into SpecialCompilerOptions and they will be removed
// FASTBuild.cs
private void AddCompileAction(LinkedAction Action, IEnumerable<LinkedAction> DependencyActions, ILogger Logger)
{
...
string[] SpecialCompilerOptions = { "/Fo", "/fo", "/Yc", "/Yu", "/Fp", "-o", "-dependencies=", "-compiler=", "/sourceDependencies", "/experimental:log" };
...
}