Is there a way how to force dropdown to always dispatch LoadData event on each open? I've noticed that LoadData events won't get called if the LoadDataArgs would be the same (which makes sense, because results would be same also).
There is no such option however you might create your own component with similar behavior:
Ah, thank you enchev, i didn't even noticed there is Popup component.
For anyone else in the future:
Another good low-effort workaround is to instead of using RadzenDropDown use RadzenDropDownGrid which invokes LoadData event on each open.