As of patch 2.1, you will need to do the following for ALL alerts.
1. Enable the alert type in the strategy settings
2. Input / Change the messages into the message boxes that you want to have send alerts
3. Create NEW alerts
4. For the alert message, input the following text as is:{{strategy.order.alert_message}}
While this method is slightly more tedious than the previous, it does ensure consistency between charts and alerts, and updates are rendered the instant orders are confirmed.
Please note, you will still get alert sent on any alerts you have disabled but the custom messages will not deliver. It will just send a blank order fill alert.
Placeholders can be found here.
Strategy Alerts
Tradingview Alerts