@Virusman - as per my PM, another minor glitch in NWNTX Optimisations.
After editing a trigger, attempting to close it results in the error message "One or more event scripts do not exist".
The workaround is to delete the script reference(s), re-open the toolset without the optimisations, then add the script back.
I think this is happening because the script drop-down is not pre-populated - it just says Script 1, Script 2...