Running a Chrome test with W3C enabled on our virtual device loud might lead to an UnsupportedCommandException error when using the Actions class.This is due to the Chromium team not having implemented the complete set of Actions methods on Chrome at the time of writing.
This error might also be presented as an unknown command when looking at the chromedriver logs for your test.
For the latest status on chromedriver's status on WebDriver implementation, see here.
Once the methods have been implemented and a new chromedriver version is released, you will be able to run Chrome tests with the Action class on Sauce.
The only known workaround is to not use the W3C capabilities and revert to older JSON Wire Protocol capabilities.
NOTE: This is not an issue specific to Sauce Labs, and attempting W3C mode with Chrome will result in the same error on any Chrome instance.