While the assign tax schedules and address correction routines are running, the customer address cards are in a state of flux. Customer addresses or tax schedule IDs may be modified or replaced. Users entering sales transactions during these processes may end up with the old, unmodified address or tax schedule ID, or they may end up with the newly updated address/tax schedule ID (Depending on whether DynamicZip processed that customer record before the user began using it). The same scenario can be said for vendor address cards and purchases transactions.
For questions on running the import while users are logged in, please see Running DynamicZip updates while users are logged in FAQ.