Please do NOT use ANY cache based plugin in WP admin -> plugins (like WP super cache, quick cache, total cache etc).
If you have any cache plugin active, pls de-activate and test if the content access issues go away.

These are the things you need to look for :

1) What's the drip start and drip end day of the protected content in dap?

2) Is the content dripped under the product to which the user has access?

3) Is the user's status set to "A" in dap Users -> Manage page?

4) Is the user's product status set to "A" in DAP Users -> Manage page?

5) What's the user's access start date and access end date in DAP Users -> Manage page for this product ?

If all appears to be fine, pls send a support ticket with us detailing what you found for this user from steps 1 to 5 above.