The descriptions under Page Edit -> Restrictions are not accurate and this is causing confusion.

The 'No restriction' permission silently applies a restriction hierarchy
View = Space View AND Page View
Edit = Space View AND Space Edit AND Page View

The Group restriction is fails for multiple groups without explanation

Recommendation -
For Page 'View', change "No restriction" checkbox to "Users with Space 'View' "
For Page 'Edit', change "No restriction" checkbox to "Users with [Space 'Create'|spacepermissions.action?key=some_space] and Page 'View' "
For both, change "Group" to "Single Group"