Many CRM implementations who upgraded their CRM 2013 organization to CRM 2015 started experiencing an issue where users were unable to see any fields on Account, Contact and Lead form. The form only used to show the command bar. This was specific to certain user.
But strangely the security role assigned to these users had read permission on these 3 entities and the data was shown on the home page grid and dashboard correctly, it was only the record forms were the issue was. Certainly it wasn’t a security role issue. Then what was it?
It turns out to be a bug with CRM 2015. The fix was to add the Read privilege on the Campaign entity in the role. I don’t know if this is related to the Last Campaign Date field on the records, but that fixed the issue.
The fix is now part of Update Rollup 1 for Microsoft Dynamics CRM 2015 so you may just update the CRM 2015 environment to UR 1 after up gradation from 2013. Below link has the list of all such fixes coming with CRM 2015 UR 1.