Unable to add Task

I've been using ToDo for a short while.  Deciding if I want to switch from Wunderlist.  About the time I had decided to make the switch, I suddenly can't add tasks.   I go to a list and the "add task" button is shown at the bottom but clicking on it does nothing.  If I select "Task" from the menu bar, everything is greyed out.  

This is just on my MacBook TODO app.  I can still add tasks from my iPhone but not on the computer.