I have a very edit/create view. When the user clicks on "Save", the user is redirected to the list view.
The model already has the basic CreatedAt, CreatedBy Observers.
Once I created and added my own observer to after_insert, after_update and after_delete, the redirect no longer works and the user is presented with a blank page.
Any ideas why this may happen? I'm not returning any values from the Observers but I followed other examples and they did the same...
Sounds like you have an error somewhere, and have disabled all error reporting (so Fuel can't catch it).
Check your Fuel app logs, and your webserver logs, for possible hints.
In general, there is no need to play with the error settings. Fuel deals with errors and exceptions based on the environment. In "production", you get a generic message (you can customize) and a log entry, in other environments you get a nicely formatted error report.
So make sure you use the correct environment ("development", "staging" or "production") when you deploy your application.