I found that it doesn't add a rest mark but if you have fewer beats than in the time signature it puts an unwanted pause in. The reason this is happening is that the autuomatic beats per measure feature I read about, is not working. If I make changes to note lengths the measures are not adjusting automatically and so I have measures with fewer than 4 beats and measures with 5 or 6 beats. This is a deadly problem, because manual adjustments like this are so time consuming and exhausting I want to send this software back and get a refund if something as basic as this is going to fail.
The graying out maybe a result of being in the wrong mode, like score set-up vastly limits the number of options in the drop down you can access.