All of a sudden Bridge is not recognizing NEF files.

Hi @alex,

Thanks for reaching out.

What is this ACR version on your machine ?
There was an issue with ACR version 15.5.0 with preferences which has been resolved in release ACR 15.5.1 .
Please update if you are using 15.5.0.
If that does not resolves the issue then share any sample file with us @ sharewithbr@adobe.com

Regards,
Bridge Team