I've never been able to post an image in this forum; but the version I downloaded is the version that people are encouraged to download at the main LMMS download site.
Windows 7.
Over many years, I've used many different versions of LMMS. ZASFx has always worked exactly the same in all of them.
But the GUI won't open in v1.2.1
alt-tab shows everything that's open, and confirms ZASFx GUI is not open.