have a look at the shared matches for both OH and his daughter and see if that helps.
From what I understand the only way to know for sure what is happening is to upload the data to another website that lets you look at the actual segments and hope that match is also there.
There are about 3 different types of DNA matches, firstly a match as you are actually related, the other 2 confuse me but are basically flukes and you aren't related at all. However ancestry apparently cuts the segments off so it might just be that OHs were chopped differently to his daughter. I really don't understand it all but she might have one or more segments that aren't a relationship and the others were cropped too much for OH.
There is a FB group that is very knowledgable but they are mainly US people (if that is an issue for you) and they will recommend using GEDMatch to look at each segment to work it out for sure.
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Toni 
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