Hi Costa,
Greeting from Syncfusion.
Query: And also the search returns incorrect results:
We have validated the provided sample and search function is working properly in Grid. By default, we have used contains operator for searching so it return all values(which contains search key).
If we misunderstood you query then share more details or video to demonstrate the issue. It will be more helpful for us to validate further and to provide a better solution as soon as possible.
Query: there is no tag allowExcelExport = "true", but even with it, the export still does not work
We have checked with our end and we are getting the 500 internal exception while exporting. By default, we have send the request to get all data(2000) from server to export the data in Grid. When using large amount(2000) of data with asynchronous cause 500 exception issue in ASP.NET Core 3.0. Please check the below reference link for more information
Regards,
Thavasianand S.