Matrix Item Imports: I need to update a field on all matrix/matrix sub items. That field is only modifiable on the Matrix Item (preferred location). If I import an update to the sub item only, it doesn't fail, but it also doesn't update. If I import an update to the Matrix item, it updates the matrix item, but not the subitems. I am reallyyy hoping to NOT have to manually update all these via the UI. Any one have any idea?

You should be able to update both types at the same time. What kind of field are you updating?

'Preferred Location'. Which is only able to be modified on the Matrix parent.

Yeah. It’s right here in an import mapping

NetSuite will not update the child item when you import an update to that field. If you import to the parent, it will update the parent, but not the child. Child only is updating when you modify that field on the Matrix Parent in the UI.

Sadly, I get "Your session has timed out. Please re-enter your information and try again." with every attempt to mass update this (native) field.

I just did this myself both ways and it worked fine. I was able to add a preferred location and then delete it for both matrix and parents.👍