FYI, this is an ongoing issue in WAB within multiple widgets. Also see: Solution for BUG-000086319. There is still no solution to this problem. I have seen this in the Query, Filter, and Search widgets, and I believe I also saw the same issue in the Screening Tool, wherein fields selected for display on the report also show commas for numeric fields despite having commas turned off in the web map. In the Search widget, regardless of whether or not a field has commas turned off, the search returns display with commas. I did discuss this with developers at the 2017 DevSummit in Palm Springs, but no solution has been forthcoming since.