EDIT - Apologies. Wasn't aware of bug report section. This has already been raised here
Tried to create the example program in "Blazor Succinctly" and received this error while carrying out data changes (Edit / Delete).
Noticed I'd created my new example with Net 5.0 and the example uses Net Core 3.1. I'd also used the latest version of Syncfusion Blazor 18.3.0.53
After plenty of framework changes and testing, I nailed it down to Syncfusion Blazor 18.2.0.54 and subsequent releases.
It works fine with versions prior to this (up to 10.2.0.48), even using Net 5.0 and EF Core 5.01, so something must have happened with release 18.2.0.54. I do notice that there is a jump in the release number from 48 to 54, so there may have been quite a change with it.
Hope you can resolve this.
Paul