Hi there Hoppers,
When your hopper isn't trading, the first thing to do is check the dashboard, and look to the right, there is a small widget with 3 buttons.
Hopper is (Either enabled or Disabled)
Buying is (Either enabled or Disabled)
Selling is (Either enabled or Disabled)
If the hopper is Disabled, it will start working completely, the link to the exchange is lost and it will remain Idle.
If buying is Disabled the hopper can still sell, and you can still do manual trades, it will simply stop automatically buying for you.
If selling is Disabled the hopper won't sell any positions unless manually ordered to do so, it will still buy automatically.
Please check this before sending in a support ticket.