GENI again started returning incomplete search results. It looks like a typical database soft error: they find one link and stop the search while they have to continue it until finding the most valuable (direct ancestor) path or till ending complete search of the entire tree. As the result they report that father of my 25th great grandmother is NOT my great grandfather, but a cousin removed 25 times????
Hugues I 'Magnus' (1057) -> Elisabeth de Vermandois (1085), his daughter.
About a month ago everything was correct, but some time ago they had the same error.