Nextcloud version: 20.0.2
Operating system and version: Raspbian GNU/Linux 10 (buster)
Apache or nginx version: Apache 2.4.38
PHP version: 7.3.25
No errors in apache, php or the nextcloud admin panel.
Auto sync/upload from Oppo F11 Pro will not work for any folder, however multiple different Samsung devices work without any issues and immediately start uploading once the cloud icon has been pressed.
I requested the user to install a dev build (nextcloud-dev-20201205) and here are the logs from the device https://pastebin.com/GqqcyXXQ