there are many reason that the developer delaying the agent comm but its depend on the agreement between developer and agency. lot of agents they didnt know what is the agreement content between their agency and developer. you cannot blame the developer if the agreed contract stated that the full comm will be paid after the first draw down from bank or others condition....Try to imaging the project is under HDA , normally the bank first draw down will be on the completion of Stage 2a ( Completion of piling and foundation works) , you will have to wait your claim about 1 year time if you sell the project during their pre-launch.
Btw there's minority of the developer in the market purposely to delay agent comm too . To be honest , my side still have around half an million comms havent get pay yet. nothing we can do actually.... just wait. haha.....