Hi @robert.newton.442rpp , welcome to Thunkable! 
In general, I would suggest you use a local table to save the Filtered Dates to avoid too many calls to Google Sheets.
Also, after you create new rows on the data source you could try to refresh the Data Viewer.
Be sure to check out How to ask Great Questions v2.0, the Community Guidelines, and our Getting Started Guide to make the best of your Thunkable Community experience!