I have a simple Select Widget set up in a web app. I'm noticing strange behavior when there is a large number of records. For example, one area has 9486 records. When I select all features, only 8,000 records get selected.

There is no reason for the discrepancy. There are no features that the selection box has missed (checked that a couple times).
This feels like I am hitting a built-in limit, but it gets a bit weird. (The features are stacked points, so the user sees what looks like 20 points, but is actually selecting a much larger number of records.)
If I zoom IN and select the visible points, I get the full set of 9486 records selected. Also, there is another project with over 10,000 records and they all select fine.
Is this a bug or a built-in limitation of this widget?
Thank you,
Randy McGregor