I use my Yubikeys all the time in OpenSUSE Tumbleweed and Linux Mint - a Yubikey 5 NFC and a Yubikey 5C NFC (mostly with Firefox). I have never had any problems with them. Mint is Ubuntu-based so they ought to work in Ubuntu. Sorry I can’t advise you on why yours isn’t working, but it should definitely be possible to get it working.