What columns do you have added to the default view for the library? I've seen issues like this before when I had forgotten to add the columns I wanted to the default view. It seems unlikely Title wouldn't be in there, though...

I also saw a similar SO question where the .load function uses an extra argument:

clientContext.load(collListItem, "Include(Title)");

You might want to try that out as well, though honestly I've never used that second argument before.

What columns do you have added to the default view for the library? I've seen issues like this before when I had forgotten to add the columns I wanted to the default view. It seems unlikely Title wouldn't be in there, though...

I also saw a similar SO question where the .load function uses an extra argument:

clientContext.load(collListItem, "Include(Title)");

You might want to try that out as well, though honestly I've never used that second argument before.