Thanks for reporting this. The Insert menu currently has two entries called Enumeration, one for a standalone enumeration and another for an enumeration inside a class or module. That’s confusing and needs fixing.
I’ve logged the bug. I’ll replace those with a single Enumeration command that uses the current context, so inserting while editing a module adds the enumeration inside that module.
For now, use the lower Enumeration entry among the member commands, or right-click the module’s Enumerations section.