Are you getting an error code when trying to launch the game? If so, please reach out to support for help on this issue?
Thank you for the update. Happy to hear you have a workaround!
Rainbow Six Siege Dev Tracker
This thread was added on March 24, 2019, with posts from Ubiflowessence, FatsharkJulia.
Thank you for the update. Happy to hear you have a workaround!