Inconsistent view of loudness meter

Hi. I have around 60 + songs I’ve recorded over the past 20 years. I started in Cubase 3 and now have 10.5 Pro on my Mac. I have recently been remastering some of the older tracks and have noticed that some of them have no reading on the loudness meter on the right side of the screen. The newer songs and some of the older ones will register, but not all of them. Is there some kind of setting that I have overlooked or am not aware of?

I found the solution to this problem. On some of the older songs I had used an older AI and it was still listed as my input. When I removed it, the meter started working fine. I’m not sure technically what the difference was, but that fixed it.