Paypal error when clicking an order button on your site: " Sorry - Your last action could not be completed."
There is currently a known issue with paypal at the moment regarding encrypted buttons:
Dashboard -› OptimizeMember -› PayPal® Options -› Account Details -› Enable Button Encryption
If you turn this option off, and also turn off button encryption required in your website preferences inside Paypal you should find your buttons work fine. While Button Encryption is disabled, we recommend that you closely monitor incoming transactions for any fraudulent activity, as the risk of fraud increases slightly without this high level encryption being applied to the HTML output in these PayPal Buttons.
We have been informed that Paypal are working to resolve this asap