Window resize and snap to layout inconsistent

I've been using Mosaic almost since launch (converted from Window Tidy). It has always worked flawlessly. Recent weeks I'm seeing windows that will not resize/snap into their normal positions. The apps are the same daily apps and the layouts are the same/unchanged and well tested. I drag to my normal layouts and windows either don't match the layout, or the resize correctly but hang off the edge of the screen. No major changes in my my system since upgrading to High Sierra, but this behavior is becoming more visible over the past 3 weeks or so.

MacBook Pro mid-2015

MacOS High Sierra 10.13.2

Mosaic v1.0.8 (80)