How many individual active(*) securities are in this account?(*) "Active" means you own shares of this security at this time.
How many lots in each security?
If you've ever terminated this process while running, restore your Quicken data file from a backup taken just before you started. The file you have with a half-completed killed transfer process most likely is toast.
Try transferring securities one selected security at a time, creating a backup of your Quicken data file after each security. This will give you a restore point in case the next transfer action fails.When you have only one security left to go select "All securities" so that any Cash in the account is also transferred.