Note that you have to right-click (terminate the tool) to add the measurement to the drawing - this might be considered to be a bug indeed. I will check if this makes sense.

I did terminate the tool with a right click - and the area was calculated but not written in the drawing.
Now I terminate it two times - and it works.

One right click makes sense to me but not two. Furthermore if I like to take a couple Area measurements in row I have to pick up the area info tool again and again (two right clicks = a final termination).

Yes, that's what I meant by 'terminate the tool' (right-click twice). I will look into that, thanks.

Quick fix (scripts/Info/InfoArea/InfoArea.js):
https://raw.github.com/qcad/qcad/master/scripts/Information/InfoArea/InfoArea.js

Thank you for the quick fix - works like a charm!