Check your scheduled tasks to see if the Process analytics log task is currently enabled, has run recently, and does not show any error.
Also do you have the setting Log via JavaScript snippet enabled? If so make sure you see it firing client side on your page and that there are no console errors in your browser. You should see some code that looks like:
<script>WebServiceCall('/cmsapi/webanalytics', 'LogHit', '{"NodeAliasPath":"/Home","DocumentCultureCode":"en-US","UrlReferrer":""}')</script>
If you don't have it enabled try enabling it to see if that works better.
Also double and triple check your permissions on the ~/App_Data folder it usually boils down to permissions.