Just responded to your Steam post, but I'll reply here as well:

The monitor overlay snapping only affects maximized windows, so what's happening here is that when you pull it straight down, Windows itself is actually restoring the window (making it no longer maximized), so then DisplayFusion ignores it. I will add a feature request to our list for an option to make the monitor selector always appear, regardless of whether or not the window is maximized.

Thanks!

I'm not sure what you mean. You only want it to snap to the splits on specific monitors?

Ah ok, thanks for clarifying! I will add that to the feature request ticket.

Yes! I'm not sure how I missed this thread when doing follow-ups, sorry about that!

On the Settings > Window Management tab, enable the "Show monitor selector when dragging non-maximized windows to split monitors" option.

Hope that helps!