I'm using CiviCRM 4.7 with paypal standard. When someone proceeds to paypal and chooses the guest option (no account) to pay with credit card, it processes normally. Yet, when returning to the CiviCRM they get the contribution page form again (not the 'thank you page') and a message that 'session expired'. This behavior is consistent across these browsers: Chrome, Edge.
Anyone seen this? Is there a setting or change within CiviCRM to prevent this? People are confused and making a second donation.