• 1 Open menu / Options
• 2 Select the category Privacy & Security
• 3 Scroll to Certificates
• 4 Click on View Certificates

• 5 Select the tab Authorities
• 6 Click on Import...
  and Open the file:
  MM3-WebAssistantProfessional/config/certificate/MM3-WebAssistant.cer

  Note

  The file only exists, if the WebAssistant was already running.

• 7 Select Trust this CA to identify websites
• 8 Click on OK
• 9 Exit previous dialog Certificate Manager with OK

Please, check this settings now:
http://127.0.0.1:8080/httpsProxyConfiguration
You need the WebAssistant - Proxy Offline Browser for this check.