Hi CrK
I suspect that you try to start the preloader while nothing has been added to the preloader's list (stabilizer is counted as an item). The preloader will not start if nothing is added because it simply has nothing to preload. So you may want to check the number of items added to the preloader ("ItemsCount" expression) before you actually start it. This way you are able to decide whether you need to start the preloader or not.
If I'm right you should see "[Preloader]: Cannot start Preloader, the list is empty." message in console log. Can you check if you see such message in the console or any other message in the moment when it does not start?
In regards of the Stabilizer itself. Yes by just adding the Stabilizer your layout transition will take at least Check frequency * Confirmations required seconds because it has to be sure it's all stabilized.
If the above solution won't help then if possible could you please send me the capx for investigation? It obviously doesn't need to be your project but if you could just replicate this issue in separate capx that would help me to investigate the issue.