There is a problem with the RadzenDropDown control when using the keyboard to make a selection. This can be demonstrated by the dropdown demo page (https://blazor.radzen.com/dropdown). Take a look at the control titled 'Dropdown with custom filter operator'. If it is empty and the down arrow is clicked to expand the dropdown list, you can type 'around', press the down arrow and press enter to select the item. But if you repeat the operation and type 'alfreds', pressing the down arrow and enter does not select the item. I also notice that sometimes more than one entry in the drop down list is highlighted and sometimes if the list has been filtered down to one item, pressing the down arrow does not highlight the item at all.