Many-to-Many relationships: Cannot edit / insert values

Hi,

I've set up a new project with Data Access and Dynamic Data, based on an existing database with several many-to-many relationships. The relationships are ​implemented as pure join tables and displayed correctly in the Data Access model. When displaying the data in the Dynamic Access application, the related entries are displayed correctly.

However, when editing an item, the related entries are read-only. They are displayed, but there's no checkbox. Likewise, when inserting a new item, the field is just empty.

Configuration:

.NET 4.5

Visual Studio 2012

Telerik DataAccess 2013.2.611.1

Any ideas?

Thanks!