Moom 3’s 'snap to edges' feature conflicts with Spaces/Desktops 'move to next space' when you use the drag-to-edge action: Both activities activate on drag-to-edge. This causes a problem wherein a window may both resize and be moved to another Desktop/Space. Not good, obviously.

Unfortunately, we have no control over this action, as it’s owned by macOS. Nor do you, the user, have any control over it: it’s always enabled, with no pref to disable it. Thankfully, there is a way around the issue, such that you can use both Moom’s ‘snap to edges’ and OS X’s ‘drag to new Desktop/Space’ features together.

The workaround is to change OS X’s activation delay for the ‘drag to new Desktop/Space’ feature. Full details on doing that are in this blog post.