Security Role for user assigned has access then says insufficient privileges

I have a client that just upgraded from CRM 2013 on premise to CRM 2015 on premise. They created a new form for the account entity and a security role to go with it. The security role has been applied to the account form, saved and published. directly after publishing I can log in as the non admin user (browser cache has been cleared) and access the form. But after a short period of time when the non admin user logs back in and tries to access the account form they receive an error saying that they have insufficient privileges. Also I have verified that the privileges are still intact and were not removed.

Any thoughts or ideas on this issue would be very helpful.

CRM Version: CRM 2015 (7.0.2.53) (DB 7.0.2.53)

Thanks,

Josh