.... [10:09:28 INFO]: nazmoo issued server command: /drivebackup backup
.... [10:09:28 INFO]: [DriveBackupV2] Creating backups, the server may lag for a little while...
.... [10:09:28 INFO]: [DriveBackupV2] Doing backups for .
.... [10:12:11 INFO]: [DriveBackupV2] Uploading file to Google Drive
.... [10:12:13 WARN]: java.lang.NullPointerException
.... [10:12:13 WARN]: at ratismal.drivebackup.googledrive.GoogleDriveUploader.uploadFile(GoogleDriveUploader.java:323)
.... [10:12:13 WARN]: at ratismal.drivebackup.UploadThread.run(UploadThread.java:155)
.... [10:12:13 WARN]: at java.base/java.lang.Thread.run(Thread.java:834)
.... [10:12:13 INFO]: [DriveBackupV2] File uploaded in 1.59 seconds (1193728.3KB/s)
.... [10:12:13 INFO]: [DriveBackupV2] Backup complete

Instruction followed from wiki.
Probably the best way to reproduce:

1. Relink account by 4 times (I switched server and try to figure why files are not uploaded to drive).
2. Backuplist "."

I will wait for scheduled upload and update here.

Can I see your config.yml? Also, what version of the plugin are you running? The latest stable version is 1.2.3.

You can only set the file path to backup to . in the new 1.3.0 beta. Try updating to this version.

.... [10:08:00 INFO]: [DriveBackupV2] Enabling DriveBackupV2 v1.2.3*

Thanks for reminding to update. I was forced to believed this message.

.... [10:08:19 INFO]: [DriveBackupV2] Hooray! You are running the latest release.

However, this version supports . I believed, by comparing two zips from v1.2.3 and v1.3.0. They both are exactly same sizes
Seems like updating solve the Gdrive problem. Appreciate your help!