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The fact that modern applications continue to work and only a handful of legacy applications fail after enabling Credential Guard strongly suggests an authentication compatibility issue rather than a deployment problem. Credential Guard commonly breaks or restricts legacy mechanisms such as NTLMv1, MS-CHAPv2, CredSSP SSO, Kerberos unconstrained delegation, DES-based Kerberos, and some third-party Security Support Providers (SSPs).
Since disabling Credential Guard immediately restores functionality, I would focus on identifying the exact protocol being used by the affected applications instead of rolling back the rollout. Review the Microsoft-Windows-NTLM, Security, and LSA event logs on an affected device and capture an authentication trace during a failed login. This typically reveals whether the application is attempting NTLMv1, unconstrained delegation, or another legacy authentication flow blocked by Credential Guard.
In most enterprise environments, the root cause turns out to be a legacy dependency rather than Credential Guard itself. Once the protocol is identified, the recommended fix is to migrate the application to Kerberos, NTLMv2, certificate-based authentication, or constrained delegation rather than disable Credential Guard for the entire fleet.