I'm not sure why this happened but I'll post my experience to maybe save someone some time. I was originally rooted. I went back to stock to take the OTA. Tried using this method this morning and although I showed SU permissions I was unable to get anything to allow SU access. I'm not sure which USB option I was in the first time but I completely reinstalled after doing a factory reset and made sure I was in mass storage mode and I'm now good to go.