Why should I start a new thread if this one was never resolved and I am still having the same problem?
I was able to fix this by finding an answer on a different forum.
Simply increase the text leading using the text format option, like so:
var format:TextFormat = new TextFormat();
format.leading = 2;
I also just had this problem and here's what fixed it for me.
The field was set to multiline, but only needed to be single line. So I changed that to single line.
There was also a -18 set for the paragraph spacing. I changed that to 0.