When calling BIS_fnc_showNotification, the correct icon is displayed but the text does not show.
This may be a new issue with 0.58 since I am fairly sure it worked before.
I have tested using the templates TaskSucceeded, TaskFailed, TaskCanceled, TaskCreated and TaskAssigned, and the issue occurs in all cases.
["TaskSucceeded", ["Job done"]] call BIS_fnc_showNotification;
I'm afraid your code is incorrect:
["TaskSucceeded", ["Job done"]] call BIS_fnc_showNotification;
Notification shows the task title as returned by taskDescription command (http://community.bistudio.com/wiki/taskDescription). However, the title is 2nd param in the returned param, not the 1st.
To mimic this behavior, push your text to the 2nd place:
["TaskSucceeded", ["", "Job done"]] call BIS_fnc_showNotification;
Note: I recommend to use task functions (BIS_fnc_taskCreate and others in 'Tasks' category of the Functions viewer) or task modules which handle notifications automatically.