I have been exporting my personal family tree from ancestry.com via the built-in GEDCOM export feature. This tree has about 36,000 members. However, when I import the GEDCOM file to geneanet.org, I happened to find a set of siblings that were essentially 'floating' in the family tree, with no recorded parents according to the website. After further investigation in the initial GEDCOM file, I found that there were 67 total people with FAMC tags attributed to them, but with completely blank values. I have no idea what may have caused these issues, especially on such a small number of the total individuals, but I am curious if anyone has any experiences with this. It may also be important that all these individuals fell into one of 10 different families. An abbreviated (and name-changed) example below shows how the GEDCOM file looks like for one of these individuals.
0 @P1@ INDI 1 DEAT 2 DATE 17 Sept 1997 1 BIRT 2 DATE 15 Mar 1927 1 NAME John /Smith/ 1 SEX F 1 FAMC 0 (etc)