Re-opening previous report from
and reply to @WhiteNoise
File storage apps such as ownCloud and Nextcloud use the Android Storage Framework. Thus their data are stored inside a sub-folder underneath /ownCloud and not inside /Documents (which is not synced per se).
It should be possible to place an obsidian vault into an ownCloud sub-folder to get it synced between mobile and desktop devices. This already works fine with the Obsidian builds on Windows and Linux, but not on Android. Therefore I assume a bug in Obsidian for Android, possibly related to the usage of the native Android storage framework.