From the error message, it appears that there is an issue with a drop-down menu within the screen. The drop-down menu might be missing or allocated incorrectly.
These messages are from a new validation that was recently put in place and the issue has always been there, we just never made our users aware of it prior to yesterday.
We are going to suppress the error message to give our clients time to resolve the issue on their screens. We will be setting an automated process of emailing the Admin of the Method account with these messages.
In the meantime, please review the drop-down menu actions associated with the screen. Within a couple weeks, the validation message be set back to be active and will re-appear for any cases of this issue. If you like one of our Support team to investigate this issue further then it might be at a charge.
Please let me know if I can be of further assistance.