Sorry, I didn't get the notifications from this thread. Cakewalk support confirmed me it's a bug in Windows 7 (they couldn't reproduce it on Windows 10), buuuut although the web says Windows 7 is a supported OS, they told me as well that they aren't too much in the Windows 7 thing, due to the end of this OS support in some months (January 2020).
I have other bugs as well, like my sound card randomly hangs up and sound a buzz (but not too ofthen): it is fixed when I open the preferences windows. So I'll deal with this until I switch to Windows 8.1 or 10 (i.e. When Firefox, Chrome and Opera stop making updates for Windows 7, like I did with Windows XP in some of my machines ?)