Thanks, Lorn! Especially for your observational explanation. It is a not too common post that such detail is given without someone else having to pull out missing information, asking specific questions that could have better been demonstrated initially.
Not Lilium, but with many bulbs, roots die over the summer and a completely new set of roots begin in the fall. Sometimes they develop extensively, sometimes not very extensive at all, in which case the real growth begins in very early spring. This second grouping would be extremely vulnerable to frost heaving.
It's kind of funny how you speak of cracks: My conditions are different, and I often have cracks of varying size at the end of the summer from shrinking clay based soil losing moisture. The freezing of the soil loosens the soil (while it re wets), and by spring the cracks of yesteryear are gone(!) Of Course, I seldom water, compare to most (who would not have so much summer cracking to begin with).
edited for spelling