@Craig_Hawkins: Insync currently errors when using a symbolic link as the local sync root folder. The default name is not required. We have this in our TODOs but we haven’t worked on it yet. Apologies for the trouble.
For the file not syncing, did the Insync tray icon show a blue circle? That means that Insync was performing other tasks first, so the file was not synced right away. How long was the delay?
For the application icon appearing in topbar/taskbar, are you not using TopIcons (https://extensions.gnome.org/extension/495/topicons/)?
For the Nautilus extension, were they installed? You could confirm by running dpkg -l 'insync*'. If they are installed please try restarting Nautilus for the extension to take effect.
For the other issues please send your logs to support@insynchq.com: How to find the log files.