I repost part of my earlier post from "other Stardock software", because this is about 2 products (WindowFX & Groupy) Original post
I noticed this "funny" visual bug about half year ago, where Groupy tabs appear on desktop before window itself (example, when you launch File Explorer with Groupy tabs enabled). It is always like this, no matter what is your settings (shorter animation, "less waiting"). I guess WindowFX will ignore Groupy tabs, so those tabs appear on desktop almost instantly when you launch (example) file explorer and then it will animate "standard window" with selected animation speed.
Software / Windows information:
Windows 10 Home - Version 1903 OS Build 18356.1, so far same issue with every build, even with official release (Win 10) So it looks like something that developer didn't ever noticed.
Groupy 1.19 Beta
Groupy-settings > Compine if possible or Always place above have same result, in both cases WindowFX ignores everything that is from groupy and doesn't animate them.