KNOWN: SCREENFLOW UPLOAD TO YOUTUBE ISSUE
We are aware that there is an issue with authenticating to YouTube. We have notified YouTube in hopes to have this resolved soon.
In the meantime, we do have a workaround to export your project file as an MP4 file and upload the MP4 to your YouTube channel using a web browser, please see link below of a knowledge base for this workaround.
Thank you for your patience while we work through this with YouTube.