I created a MovieClip symbol in flash containing a dynamic TextField and a background. I exported it in a SWC(using this method) and I'm trying to use it from flex. When I try to change the default value of the text field the new value is not displayed(indeed the default value I put in flash is cleared on screen, but in the debugger it shows that the new value is set in the text field)
If the debugger indicates that the value is being set correctly, then perhaps the problem is that the textfield is unable to display it because of a missing font?
Check that you have correctly embedded the font in your SWC (check the Adobe docs here for more info on embedding fonts).
Hope this helps...