Hi Henryk,
Thank you for your interest in Syncfusion Product.
Our Essential Grid have been revamped to provide an enhanced support to extensive client side functionality. Our current [7.403.0.20] grid uses new MvcStaticResourceManager to register the css and scripts required to display and add functionality to the controls.
Add the Resource Manager to the Site.Master page under the tag as follows.
.....
<%=Html.RegisterStaticResources() %>
Please refer sample from the below location.
http://files.syncfusion.com/support/grid_mvc/Incidents/v7.4.0.20/F91281/MVC_GridSample.zipPlease let us know if the reported issue is resolved at your end.
Regards,
M. Balaji.