When the search matches the very first row this row isn’t selected and you cannot move down to the next match (arrow down). It is only possible to move up to the very last match.
I checked one of your blazor Demo called “Grid Colunm Menu” (@page “/grid-column-menu” ) and you can reproduce it there (search for “Saavedra” for example)
I have tested the exact same demo and I confirm the reported behavior from you.
Also I will add a work item for this scenario and we will work to fix this issue as soon as possible.
Please, do not hesitate to contact us if you have any additional questions.
Smart UI Team