debugging access

Hi folks, I have a SP site with some groups that have external members. I added 2 users from 1 external domain as guest users in my org and once they accepted the invite I gave them Read access to the SP site by adding them to the group. Works fine for 1 user but the other user keeps getting a permission denied and a "request access" dialog. I delete the guest user from my AD and recreated him but still the same. If I go to my "Check Permissions" and check both users it says they both have Read access via the group I added them to. Any ideas on how to troubleshoot further? Thanks