Gmail notifications led over wifi

In the past 3-4 days i've had a problem with my razr hd gmail over wifi. If I receive an email on my gmail acct and read it on my pc it will not clear on my phone. If I connect my phone via 3g/4g it will clear it. On wifi I have to manually open the notification and swipe it before it goes away, but even then it still shows unread in the gmail app.