We are having an issue where the Last Activity of the Contact is not showing up in the App. I can see other details like phone, job title, Opportunities and Cases. The Last Activity area has 5 scrolling dots like its looking or searching but the Last Activity never loads. I have looked at all the usual suspects where Synchronization settings are concerned. 

It may be a customization that was made. I know out Parent Customer field on the Contact was re-purposed and the relationship to the Account was removed from that field. I am trying to track down the affects of putting that back in the OOB configuration so I can show the related Parent Account.

So I am thinking that maybe a customization to relationship was modified on the Phone or Task records but nothing is jumping out at me. Thoughts?