We have a Server 2012R2 box hosting a single network share. Somehow, some files that got saved to this share got encrypted using what I can only describe as a "self-signed" EFS certificate. The cert was not issued by our CA, and does not have our usual recovery certificates attached. The matching certificate can be found in the user's personal cert store on the server. However, all attempts to decrypt the files have failed. See this screenshot:
Any ideas out there?