Trying to resolve email SSL certificate problem

Hi,

I've just installed AVG Internet Security 19.8.3108 (build 19.8.4793.544) onto a new laptop and am trying (again) to fix the problem where my email client complains about invalid SSL certificate. I've tried to follow the instructions here but when I click the Save button to export the certificate I get an error message. There have been a couple of variations along the lines of Object not found, RPC error, and the current one is: 
Error while exporting the certificate
Invalid parameter was passed to a function.

Any ideas how to solve this?