I'm getting an exception while using the text filter. This happens, when I twice type in a word, in the text filter of GridExcelFilter, that doesn't exist in the column and then press enter. The first time the filter-dialog disappears and nothing happens. The second time i get a System.ArgumentOutOfRangeException.
You can try this with your example "Optimized Excel Filter_2015". You only have to change this line: "filter.AllowSearch = true;"