I finally got around to looking at this profile. It's the last Wilson profile in that GEDCOM you uploaded. Wilson-11137 to Wilson-11141 are all living. The last non-living Wilson you added before Unknown is George Wilson. Since the rest of the GEDCOM appears to be intact, it doesn't look like it's a matter of an "exploding" GEDCOM.
In my own GEDCOM uploads, when I have ended up with a single isolated profile, or a small isolated cluster of profiles, it turned out to be because I skipped importing a profile from the GEDCOM which turned out to be the only link between that/those isolated profile(s) and the rest of the GEDCOM (and, eventually, the main tree).
There are a couple of possibilities which suggest themselves:
- On WikiTree, when you add a sibling for an existing profile, the system automatically creates a profile with the same last name and a first name of "Unknown" as the father for the two siblings. If the system you got the GEDCOM from did the same thing, then this unknown profile may be the same kind of placeholder profile.
- Another possibility is that the profile may represent a Wilson offspring who died before even being named. (I have a couple of cases like that in my own family.) In that case, the profile may have been isolated if the parents already had profiles on WikiTree when you imported the GEDCOM so you skipped them.
If you still have the original data in genealogy software, or another genealogy site, then you may be able to figure out who this profile represents by looking for those kinds of cases.