This happens because of order of execution of javascript in new AjaxReRender method (LazyLoad).
In this new methodo, javascript execution is done asynchronously, in other words, doesn't wait/block the execution.
We are looking for solution to control this better.
For now, if you have error's in your application, you can change to old method:
delphi code
CGRenderAsyncMethod:= rramOldMethod;
On create of mainform.
Best Regards.