So, I have the same problem but the solutions provided here don’t seem to get me anywhere.
I had sketchup installed on my Macbook before and everything was fine. Now I had to change to a Win 10 PC and I cannot resize anything. Btw, was it always called Sketchup Make? I get confused as to if I’ve installed something else by mistake… So here’s what happens:
I start a new drawing from a template and then import a .png. It has a scale written on it so scaling should be simple. I use the tape measure tool (and click ctrl before) and then I’ve tried both clicking to finish the measure and just start a measure and try to click the box to enter a lenght value. The problem is that the box is un-clickable. I just can’t click to enter values.
Ctrl or not doesn’t change a thing. What am I doing wrong? This worked just fine on my old machine.