Storagelimit is shown as -2 when using external storage app

[ntimo]

Steps to reproduce

1. Active the external storage App
2. Mount a storage (I only tested webdav)
3. Set the mount point to /
4. Open your iOS Nextcloud App and look at the storage limit

Expected behaviour

It should show a unlimited max storage like the web version of nextcloud does

Actual behaviour

It shows -2 here is a screenshot:

Server configuration

Operating system:
Ubuntu 16.04

Web server:
Nginx

Database:
Mysql

PHP version:
7.2.4-fpm

Nextcloud version: (see Nextcloud admin page)
13.0.4

Updated from an older Nextcloud/ownCloud or fresh install:
fresh installation

Are you using external storage, if yes which one: local/smb/sftp/...
webdav mounted to /

Are you using encryption: yes/no
yes

[nextcloud-bot]

GitMate.io thinks possibly related issues are #4730 (Storage), #3789 (External storage), #8363 (enabling external storage), #3720 (Issues with External Nextcloud Storage), and #6529 (External storage issue).

[MorrisJobke]

This is an issue within the iOS app. Thus please report it to the maintainers of that app in its repository: https://github.com/nextcloud/ios