Error encountered while signing: Windows Cryptographic Service Provider

Anyone else having an issue signing PDFs using a DoD CAC and Adobe Reader DC version (2015.16.20039) with ActivIdentity ActivClient (version 6.2.0.205 w/ FIXS1512026)?

The specific error message is:

Error encountereed while signing:

The Windows Cryptographic Service Provider reported an error:

The operation completed successfully.

Error Code 0

Reverting to Adobe Reader DC version (2015.010.20060) resolves the issue but obviously isn't a viable long-term solution.

Thanks!
Dan