Been there,done that,still the same problem
Well, it's not FL (or FL by itself). Would you mind posting a copy of your project (or send me a pm)? Just to inspect it to make sure something has gone unnoticed? Based on everything in this thread, just about everything specific to FL has been ruled out except human error & random bugs. If the export comes out fine on my end, then you would just need to find the problem on your pc or its settings
Is it possible that this fl studio version I use has this problem ? If I install fl studio 12 will I be able to open this project I made in FL 11 ???