Light Shafts Flicker in 4.19 compared to 4.18

Per Licensee:

We have noticed that the volumetric light shafts have become much more "flickery" and unstable compared to 4.18.3. This is visible in just the empty project with an unmodified engine...

The flickering/shifting is much more rapid and unstable in 4.19, which is undesirable in our game. We haven't dug in to see if there are any obvious changes yet, but what can we do to tune this behavior?

1. Open new default level with starter content in 4.18
2. Delete BP_SkySphere
3. Rotate directional light to place sun near horizon
4. On Directional light > Light Shafts, enable Light Shaft Occlusion and Light Shaft Bloom with default settings
5. Select Atmospheric Fog, increase Sun Multiplier to 3.14
6. Position camera behind Desk and Chair meshes to see light shafts
7. Save and close project, Reopen as a copy in 4.19

Result: Shafts of light are noticeably more unstable and jittery in 4.19 (See attached GIFs)