Incremental build with Ninja results to - no work to do

I have followed Getting Started to build swift (ninja & sccache) and created a Xcode project for Standard Library.

Building swift-stdlib-tool with Xcode works. I have made a change to a swift/stdlib/public/core/Bool.swift that should break some tests.

Changes are committed but ninja rebuild for swift-stdlib-tool results into ninja: no work to do. Rebuilding everything throws an error.

What am I missing? Any help would be appreciated. Thank you.

Build Swift:

$ swift/utils/build-script \
  --skip-ios --skip-watchos --skip-tvos --swift-darwin-supported-archs arm64 \
  --sccache --release-debuginfo --debug-swift-stdlib --swift-disable-dead-stripping

Create Xcode projects:

$ swift/utils/build-script --swift-darwin-supported-archs arm64 --xcode --clean

Rebuild stdlib-tool:

$ ninja -C ../build/Ninja-RelWithDebInfoAssert+stdlib-DebugAssert/swift-macosx-arm64 bin/swift-stdlib-tool
$ ninja: Entering directory `../build/Ninja-RelWithDebInfoAssert+stdlib-DebugAssert/swift-macosx-arm64'
$ ninja: no work to do.

Rebuild everything:

$ ninja -C ../build/Ninja-RelWithDebInfoAssert+stdlib-DebugAssert/swift-macosx-arm64
$ ...
$ ...
$ $ABSOLUTE_PATH/swift/lib/ASTGen/Sources/ASTGen/Types.swift:139:47: note: use 'parameters' instead
    return self.withBridgedTupleElements(node.arguments) { elements in
$ error: fatalError
$ [11/848] Building CXX object lib/DriverTool/CMakeFiles/swiftDriverTool.dir/sil_opt_main.cpp.o
$ ninja: build stopped: subcommand failed.