Hi Lisa,
Your Filter Query will be different from mine. You have to find out the Internal Name of your "Start Date" field. The error that you are getting indicates that the field name is different.
-Open you list in SharePoint
-from the Gear in the top right select List settings (if this is a Document Library, then select Library settings)
-in the section named Columns, find the field you want to filter on. In the example you gave, it was called Start Date.
-Click on the Column and you should see a screen similar to below:
Internal Field Name is at the end of the URL
If you look at the above URL, you will see Field= followed by the Internal Name of the field.
The name that you find there is what you need to change in the Filter I gave you.
If it still does not work, then remove the filter completely and try just part of it such as:
Start_x0020_Date ge '@{formatDateTime(utcNow(),'yyyy-MM-dd')}'
where "Start_x0020_Date" is changed to what your Internal Field is named and
"ge" means "Greater than or Equal to".
If the Filter is running with no errors but you are getting no results, try changing "ge" to "le" (Less than or equal to). You are just trying to see if Filtering is working at that point.