My flow worked for months and all of a sudden stopped. I have confirmed the flow works perfectly if I remove the filter query, so I know that is what is causing the error and I know it's not due to the formatting of the field since it was copied from the Order By field, which is working.
I have tried adding spaces before and after "gt" with not luck. Below are screen shots of the error message, the flow, and the SharePoint settings page for the date field.


