Now tell us the rest of the story.  The grandchild must not have been named as beneficiary, or "tied up in probate" would not be an issue.  What happened to the money between 2017 and 2019?  Was it distributed to an estate IRA account?  Are you sure that no cash distributions were taken?  Did the money simply pass from IRA trustee to IRA trustee to IRA trustee?  Had the grandfather reached RMD age yet, or does they 5-year rule apply?