Unable to select column as Quick Metric Base value

We're trying to add a Quick Metric to our report but we've noticed that we cannot seem to select any columns from a table in an existing report. However, importing this same datasource in to a new report and creating a new Quick Metric, we are able to select columns.

The datasource is a spreadsheet with the data imported in the report  in both cases. 

We are trying to understand why this is the case and how to resolve this in our existing report. Can someone explain when a column may not be available in a Quick Metric as the Base value?

Here is a video example. Selecting the field does nothing.

In the new report with the same datasource, this is possible