Airsonic does not find media folder

## Problem description

I am having trouble setting up a fresh installation of Airsonic-advanced, specifically, adding the Media folders.

Under Settings -> Media folders, I've set the MEDIA type folder with the name Music to point to my music folder, which is a WebDAV mount. However, next to the entry, it says "Folder not found". If I copy-paste this path into a terminal, I can eg. `ls` the path successfully, so the path is correct.
If I click on "Scan media folders now", a text saying "Scanning files: 0" briefly appears in the side pane, but nothing seems to actually happen. The log has the entry " Scanned media library with 0 entries", which is obviously incorrect as the supplied path has plenty of files.

How can I get Airsonic to recognize my files?

## System information

* **Airsonic version**: 11.0.0-SNAPSHOT.20220418221611
* **Operating system**: Debian 11 5.10.106-1
* **Java version**: java 17.0.2