How To Debug
Ideally, users do not need to debug anything. But if something bad happened, we have to dig into details.
Easy: Export Sync Plans
See here.
Medium: Desktop: Check Console Output Directly
...of desktop and Android.
See here.
Medium: Mobile: Use Obsidian vConsole to Check Console Ouput Directly
...of mobile (iOS and Android).
See here.
Advanced: Use Logstravaganza to export logs
This method works for desktop and mobile devices (iOS, Android), especially useful for iOS.
See here.