Hi Pandazzz123, has your issue resolved? If not, hopefully a product expert can help you soon.
There is nothing particularly special about https/ssl forwarding. so it should just work.
chances are you are just missing a field somewhere. eg. https is usually port 443, so if you didn't remap 8888 to 443 in the port-forward rule, could be that IIS-6 is never getting the incoming traffic on the port its expecting it to arrive on. Or perhaps you forgot to include 8888 in the URLs to your site? ie. https://your.site:8888
otherwise https will got to 443 by default, and you'd need to set up a port-forward for 443 to 'somewhere'.
There are endless possibilities to plug things in slightly askew. tcpdump / network traffic / Diagnostic->Packet Capture might well tell you what is arriving/being-forwarded where and help you debug it.
Or just take a Technical Support Report and forward it to support, they'll soon sort you out.