I tried to make italian meringue and it was all going well until the meringue, (with the sugar syrup added), just didn't thicken and turned into 'royal icing'. Next time, how do I make it and what can I do to rectify now?
Try this: separate the white from the yolk 3 or 4 days before you want to make meringue. Keep the white in an hermetic box in the fridge and take them out of the fridge one hour before you begin. So the egg white foam will be more stable.
Another trick is to add some drops of lemon juice to the egg white right before you beat them.
I had this exact problem and I fixed it by beating the mixture on a slower speed. At first I was beating on high speed which I think was beating all the air out of it (ironically!). Try beating in a smaller container so the mixture is more condensed and on a low whisk speed for more time.