Part of the launch email's code or link is missing

Look at Subject and Message in the Launch Email panel on the Subscribers screen. Earlier versions deleted a % together with the two characters after it when both were digits or letters from A to F, so an opening code typed as 20%DEAL was saved as 20AL, and deleted anything in angle brackets, such as an address written as <hello@example.com>. Both boxes now keep what you type, but what was saved before stays as it is: type the lost part again, press Save changes, and use Send test email to see it.