Hi Patrick,
These MX_PERSON entries are usually generated in a toIdentityStore pass, when you try to update an existing MX_PERSON, but the entry does not exist. If you put a condition like "changetype=modify", it will give you an error instead of creating a new entry.
The mskeyvalue 'MX_123456', looks like a pending value object to me. Maybe you can check the tasks that can generate pending value objects, but incorrectly put a 'MX_PERSON' as the entry type of the pass.
Cheers
Chenyang
