This may not be your issue, but I had a similar problem yesterday. I am just getting started with the Telerik MVC stuff, and I created a grid that would read data (from database-first EF model) but would not add or update. No errors, just would not do anything.
I tried to add a record to my table manually in SSMS and got an error (Primary key cannot be null) because the primary key on the table ("Id") was not set as an Identity field, which is what I had indented. I changed the table, updated the EDMX in my project and then the grid worked. I was able to add, edit and delete.
Note that this I used the Kendo grid scaffolding helper in Visual Studio 2015 to do this and did not have to add or change any code manually to make it work.