Information on the bug can be found here:
It came to our attention this bug was negatively impacting the checkout flow for some users. If values were autofilled via Chrome's built in functions, the radio button for selecting a returning or guest customer would become unchecked. After submitting the form, an error asking for a password would appear. If the form was then submitted again, it worked. We added autocomplete="off" to the account type and payment type radio buttons on the checkout to fix this issue.
If you're on version 1.0 or 1.1, you may need to update your store's checkout template in order to see the changes. If you're using a customized twig template for your checkout, you may want to add autocomplete="off" to your radio buttons to fix this issue for your customers using Chrome.
Please let us know if you have any questions. We're always working hard to keep your store running smoothly.