Thank you for pointing this out - it is a bug which our developers will address immediately. For the time being you can continue working in the same manner as before by adding the initiator and updated controls from the .aspx in this particular case. If this will be a major slowdown for you, we can provide you with custom build once ready. We have updated your Telerik points for the involvement.
Sorry for the inconvenience once again.
the Telerik team