There are additional things that must be done since the IOS change, however they also leave a 'warning notice' which is usually just in BLACK (at the top of your ad account where ads are created) that is something you can simply clear if no action is needed. If there is a warning in RED in that same area, that usually mean you MUST take action to fix the problem.
Here's a quick video you can watch to verify if you've done what is needed or not: https://soapbox.wistia.com/videos/JuTVi5pouJ
What has changed with Facebook since the iOS update:
- You need to verify your domain with FB business manager
- You need to setup your events manager for the new changes and there are several steps here
You can simply go to this module (link below) and go through the process skipping anything you already done and doing what you have not already done.
Once you've accomplished that you should be set to go, but it may be worth jumping on a support call.