DataTable doesn't properly determine number of rows in run mode or web deployment, works in test mode

I've tried manually setting the number of rows to a constant value, which results in that number of rows being shown if available or the max number of rows plus an infinitely loading row. Setting the number of rows to unset or to the number of list items for the page variable or the action output variable did nothing. Making a separate page variable for the number of rows and setting to that did nothing.

I experimented a bit with using a text field and button to manually set the number of rows on the fly, but it seems it only generates off the first instance of the variable, whatever default value I set. Changing the value on the fly does nothing, even in test mode.