Why am I getting this error? "Cannot read properties of undefined"

After Vision released version 6.0, there has been an issue with saving the shipping address in some cases. ShipLeap may not be able to read the addresses and may display the error "Cannot read properties of undefined". To correct this issue until PrintSmith fixes their error (bug) permanently, click the OTHER checkbox and save the invoice. Try to read the address after doing this.

If this doesn't fix the problem, please double check that the username and password you entered in the PLUGINS section for Vision is correct.