Hi Josef.
I’m not sure what’s going on here. On the Mac version, doing what I would normally do, I don’t get a problem and Parent is searchable.
What I did…
-
Added the keyword Parent to the hierarchy list…


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Added the keyword Child inside Parent…


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Typed
Childinto the keywords field…

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Selected the suggested
Child < Parent…

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Accepted the suggestion, which gave me this…

Then I went to the search field and started to type Parent…

Is that what you did? If not, can you give us a step by step list like I just did? We need to establish if this is a Windows only bug or whether you have stumbled across a different way of doing things that DxO hadn’t thought of.
Oh, and is this a RAW file with an XMP sidecar or something like a JPEG?