Squid proxy certificate error

[kenj05]

Hi folks, I'm having issues with my squid proxy with SSL. I enable the Transparent proxy and MITM. I also install the certificate on the end user unit so that they can able to access google services websites. However, whenever they tried the whitelists websites (ex. google.com docs.google etc.) they were getting a certificate error. I tried to clear the cache but still the same. I tried also to delete the package but whenever I reinstall the package my config are still intact. Take note I already disable the Keep settings/data before deleting the squid package. Any suggestions or feedback is appreciated. Thanks!

version: 2.4.5 p1

Error:
(92) Protocol error (TLS_code: X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY)
SSL Certificate error: certificate issuer (CA) not known: /O=pfSense webConfigurator Self-Signed Certificate/CN=pfSense-5fbd0d7ac18c6

Note: It was working fine even Transparent proxy is enabled and MITM with Splice All config then suddenly it got an error with certificate.

[kenj05]

Anyone? Please help me pfsense guru? Should I try to delete their browser cache, cookies and history?