Solved
Google Drive Backup Failed - Beta 5.4.5b
The Google Drive Backup feature of Beta 5.4.5b appears to fail if an apostrophe is used in the device name. Tasker is able to create the Tasker\data\backups folder but never creates the subfolder with the device name. My device was named "Phil's S8". After changing the name to "Phils S8", the device folder and backup file were created correctly. I suspect this issue is caused by the apostrophe being interpreted as a delimiter.