RDS webcleint ssl

I have setup Windows server 2016 with RDS and the new httml5 webclient. Everything works great except when the ssl updates
the client can login but when they try to run app they get a SSl thumbprint error. Clearing the browser cache on the client fixes it.
I am updating the Web SSL and the RDS webaccess, gateway, broker session host and running Import-RDWebClientBrokerCert
any ideas, anyone else having this