Webpage Failing to Display Properly Intermentially

I'd start with the browser developer tools (F12:Network) to track the requests to see what the browsers sees when the requests fail.

Otherwise, you need to use

K12783074:  Decrypting SSL traffic using the SSL::sessionsecret iRules command (12.x and later)

to get decrypted SSL data.

On 15.x (and later) you can use the F5 tcpdump SSL plugin to get the same information.