When a user is on the AdvoLogix Setup tab and clicks on the CT SOP sub-menu, they see a gray screen with a sad face.

Why am I unable to view the CT SOP sub-menu from the AdvoLogix Setup tab?

The issue with the CT SOP page not loading occurs due to the Clickjack protection being enabled for custom Visualforce pages in Salesforce setup. There is also a Salesforce known issue that impacts viewing a Visualforce page in an iframe in Salesforce presently. To resolve this issue, any of the 2 paths can be followed:

PATH 1: (considering Clickjack protection cannot be turned off due to security concerns)

1. Go to the gear icon >> Setup >> Quick Find: Session Settings
2. Scroll down to the section named Trusted Domains for Inline Frames
3. Click the Add Domain button to whitelist the Salesforce Visualforce display domain
4. Enter Domain = *.force.com
5. iFrame Type = Visualforce Pages
6. Select Save Reference Links:
   1. Official Salesforce Documentation - It mentions if Clickjack is enabled for the Visualforce pages, "...then under the whitelisted domains for Visualforce inline frames, add the trusted external domains where you allow framing..." (the above steps do the whitelisting) 
   2. Known Issue - To receive notifications when Salesforce updates the status, click on the link above and check the This affects me checkbox.

PATH 2:

1. Go to the gear icon >> Setup >> Quick Find: Session Settings
2. Scroll down to the Clickjack Protection section
3. Uncheck the Enable Clickjack protection for customer Visualforce pages with headers disabled checkbox
4. Select Save