Membership not fully assigned in some cases

We have some instances where membership doesn't appear to be assigned fully.

When viewed in 'All Members', the correct membership is assigned to the user, but when they login, they do not have access to the functionality that they should have, e.g. menus specific to the membership (through protection rules).

Also, when viewing the membership page, instead of seeing the option to 'cancel' their membership, they see 'signup'

Could you please have a look at this?