There are a few reason why The Detective decides not to watch your prints.
Notes: Whenever The Detective is not watching your prints, you are not using Detective Hours.
1. Your printer is not actively printing
For obvious reason, there is no point to watch a printer when it is sitting idle or paused.
2. You turned off "Watch for failures" option
There is a toggle right below the webcam feed box to let you easily turn on or off watching.
3. You told The Detective not to alert for this print
When you receive an alert, you have an option to turn off watching for current print only. This is very convenient when you have a print that is causing excessive amount of false alarms. Once the current print is over and the next print starts, The Detective will be back on the duty to watch prints for you.
4. You have run out of Detective Hours
The Detective Hour balance for your account is displayed on the right hand side of the navigation bar. When it dips below 0, The Detective will stop watching your prints. There are several ways to get more Detective Hours.