Every time I open one of the LibreOffice applications, I get a messagebox saying that the .odt and .ods formats are not registered to open in LibreOffice by default. But they are. I'm using the Microsoft Store version, which I assume has something to do with it.
FWIW, I found out that LibreOffice uses this function to determine the current file associations: https://github.com/LibreOffice/core/blob/3c91fb758a429f51b89dfe9cea088691ced6d0c1/vcl/win/app/fileregistration.cxx#L60 I did a quick test, and the result of QueryCurrentDefault on my machine is AppXfgjcm55vr2nwmdhvw8b6y0rt7d5rfcqd for .odt and AppXht95ecfd285dyhzt1hr1cr7czz4bg2e5 for .ods.