Latest Rotobrush versions create worse results than Classic version

After days of research, I can't find anyone else suffering this issue. Clearly there's something wrong with my After Effects settings or my computer because I've uninstalled and re-installed the latest After Effects apps several times (including Beta versions), and I've experimented with a variety of footage, each in its own project. The subpar results are roughly consistent.

When I initiate the Rotobrush process, regardless of version, the tool quickly recognizes the subject that I'm removing from the background and needs very little help creating the outline. But within 1 frame of starting the propagation in Rotobrush 2.0, the outline dramatically shrinks and continues to do so until the outline disappears, usually within a few frames. If I stop the process after 1 frame to correct the outline and "remind" the tool where the ssubject is, it returns to the diminished outline on the very next frame. Beta version 3.0 creates even worse results: the outline of every frame following my initial outline looks corrupted. On the other hand, Rotobrush Classic (1.0) follows the subject pretty closely. Please see the examples of this issue in the attached screenshots.

What am I doing wrong or what's wrong with my system?