Expectation:
gradle clean should always work

Observed Result:
occasionally, gradle clean fails with
FAIL: Cannot find /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.1.sdk

even though the latest xcode command tools are installed.

Further investigation revealed that the build dir got into a state that prevented any gradle target from executing successfully. Removing the build dir with the following command helped:

rm -rf build

Perhaps we can modify the gradle.build clean target so it skips the steps that fail.