The Inv Distribution Acct and Inv Distribution Dept fields are marked as Hidden in the dictionary. Use the /a parameter on the GridView shortcut to show all hidden fields and you can get everything when doing the view on QC vendors.

Activity fields in Payables such as Last Payment date are not editable on Vendors, unlike Statistics fields such as YTD Payments. Therefore, Activity fields are not importable either.
If you want these dates in Payables, use GridView R/W.