Didn't work for me either and I do have the pro subscription.
I had to manually bring up the taxi diagram both at start up and after landing (unless of course I was taxiing at over 40 knots).
This might help as well. Are you seeing the geo referenced function? App age looks to be an issue too.
I bought ForeFlight Pro but geo-referencing isn't showing up.
Follow these troubleshooting tips:
Go into 'Accounts' and confirm that your plan reads 'ForeFlight Pro'. If not, wait 10 seconds for the plan to download to your device. If it still doesn't show up, try signing out of your account and then signing back in.
Go to the 'About' screen, located in the 'More' tab on the iPad and in the 'About' icon on the iPhone. At the top of the screen is the version number - make sure it reads 3.9 or higher. If it reads 3.8 or lower, you'll need to update the app from the App Store.
Go to 'Downloads' and make sure you have downloaded the latest version of the Airport Database and Terminal Procedures.
Make sure you are viewing a plate or diagram that has geo-referencing. Geo-referencing is not available on arrivals, departures, text documents, and airports outside of the United States.
If you see the faint blue box but do not see your aircraft position, that means your GPS is having a problem getting a fix. See our GPS tips for help.