remote backup stopped because Filesystem quotas are enable?

Hello,
i configured WHM to transfer backups remotely to another acocunt via FTP. everything was fine until yesterday while i got the following email:
Backup Halted on: xxx.xxxxx.com
The exact error was: The store local backup option is disabled and no active transports exist. Please see "Backup Configuration" in WHM for more information.
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i didnt change anything since a while.
The only thing i can find in that backup section is:

NOTE: Filesystem quotas are enabled. To prevent performance degradation, quotas will be automatically disabled on non-root filesystems which contain a backup destination.

Not sure what this means as I never saw this error. May this be the problem backup stopped? If yes how to fix? Or are there any other problems?

thanks for help!