Hi Aaron Nash, GISP
This behavior was actually logged as a software defect
- BUG-000123249 - Exporting an attribute table to a CSV file from a query layer created via the Query widget in Web App Builder for ArcGIS fails, returning no error message.
I did test the same in ArcGIS Online and it looks like the issue does not occur there, if this workaround works for you.
Hope this helps,
Kaitlyn