Opportunity Permissions for Non-Admins
For non-admins, remove the ability to assign a permission at the creation of an opportunity. We've had users permission themselves at creation and because they're not an admin, they don't have the ability to adjust or see any permission on that particular opportunity. At the creation of opportunity a permission ability for non-admins creates a situation, if they only select themselves, where it can't be adjusted or seen by other users.
Chad Rice commented
It seems odd that non-admins have a one-time ability to set permissions which may then not be seen by other users.