@VMlabman
Under Backend tab for the pfsense-01. you need to select a CA and select the client certificate that you have generated for your pfsense-01.
Under Frontend tab under SSL offloading, select the ACME generated certificate under Certificate.
Check if those settings fixes the issue you are having.
Also I recommend watching the following youtube:
How to Setup ACME, Let's Encrypt, and HAPRoxy in pfsense