Steps to reproduce:
 - Create a standard Item that checks a port or service status.

 - Create a trigger using the nodata() function.
   Example expression:
   nodata(/247054.cloud/net.udp.listen[443],2m)=1

 - Disable this trigger via the Zabbix Web UI.

 - Wait for 10 seconds, then Enable the trigger back.
 
 - Make sure that no data is arriving for this Item (the data flow is stopped).

Result:
The trigger switches back to the Enabled state, but it completely stops working and freezes in the OK state. It never transitions to the PROBLEM state on its own, ignoring the fact that there is no data.

The trigger will only start working again if you manually modify and update the expression text (e.g., changing 2m to 120s).