Angular JS doesnt update the view even though the model is updated

Question

I have been struggling to see this behavior for past few weeks where the angular JS model has been updated but the UI doesnt get reflected in the multi select box.

Absolutely no errors and the data model has all the values it needed . I tried reloading controller and also doing a refresh inside controller to take changes.

tried $scope.$apply() as well and its of no use. If anyone from angularjs team is ready to take a look, we can discuss over call and i can share more about the code. Unfortunately due to sensitive information i cannot copy paste the code here.

editing main question:

example: I have an object something like this. var clusters = { available: [], selected: [], } and have 2 multiselect controls. One will show all the available ones and when user selects one it will be pushed into selected list to display in second multi select control . for the first time when page loads, if the user already selected anything, I will get this data from db. and try to display to the user what he selected previously. This is where , angularjs doesnt bind the values in the selected list when shown. The UI doesnt reflect i even though i successfully added the list in the array(selected).