This is still a great mystery for the mainstream. It is widely assumed that the 100,000 year eccentricity cycle, which is only a 1-5% change in distance from the sun, is somehow amplified to account for vast 5km high polar glaciers. The mechanism hasn’t been well established. Even more demanding, is the explanation for the sudden release of carbon dioxide back into the atmosphere to give extreme global warming during deglaciation. This is the yet unknown carbon cycle.
The exotic gravity forcing hypothesis dovetails with the scientific evidence that inclination is a better fit to the glacial data than eccentricity to give an explanation which is not dependent on the change in insolation from the Sun.