At least in SU 2017, I don’t get that. When I first click, then move mouse (no button pressed) I get the prompt Length
Let me try again in 2016. Same here too.
BTW, which version are you using? Your profile doesn’t say either Make or Pro, or which version.
I simply can’t get it to do what you are describing. It does for me just what I said in my first response to you.
It’s possible that @DaveR might be able to help you using a remote connection so he can see and/or demonstrate how to use the tool. Or if you have or could download the free TeamViewer program, I could myself (but not tonight - bedtime here now in uk).
PS. AHA!
I have at last reproduced what you describe. But only after repeated attempts. However, once it has started, I can do it again - every time, even after a SU restart.
That is indeed weird. And may qualify as a bug - certainly very odd.
PPS. Try restarting your computer - that might fix it.