Hi leks,
Thanks for using Syncfusion Products.
We can able to trigger the server side event (“OnValueSelect”) of autocomplete when using autocomplete control inside Bootstrap Modal.To trigger the server side events of the ASP.NET controls,we need to refer
“ej.webform.min.js” script file.
For your convenience, we have prepared the sample with rendering of autocomplete control and asp.net button inside the bootstrap modal and please find the sample link,
Sample Link: Sample
Could you please check with the above sample? If still you face the problem, please revert us by modifying the sample based on your application along with replication procedure. This would be helpful for us to serve you.
Please let us know if you have further query.
Regards,
Kasithangam