I've noticed a problem with the Google Analytics integration on my site. When I have the Analytics tracking code added into the additional settings area of the contact form, the success message doesn't display (but the email is sent). I've tried both the old and new styles of tracking code as seen below:
If I remove the tracking code, the success message is displayed as normal. You can see the problem here: Test page. This page is set up with the tracking code; the contact page is an example of no tracking code.
I found a few other related questions, but none of the answers I saw solved this issue.