NextcloudPI Backup manually download

Nextcloud version: 18.0.2.2
Operating system and version: NextcloudPi v1.23.1

After i made a backup via nc-backup in the NextCloudPi ConfigPanel i tried to download it via the “backups app” in the config panel.
2020-03-23 19_14_39-NextCloudPi Panel

After pushing the butten on the right for "download I get the error “Unauthorized download”.

Has anyone an idea how i can manage this?

Also sometimes the page https://IP:4443/?app=backups doesn’t load or load really really slow. It’s just this page, every other page in the config-panel works fine.

There is nothing in any log.
Thanks in advance!
Fisher