Perhaps you can work around the problem like this:
Create an action which changes white to red, so you end up with an image which is black and red with transparent background. You could for example use Channel Mixer.
Run the action on all the images.
Trace to 3 colors with Ignore White ticked.
Expand the traced image.
I don't believe you can accomplish this with Illustrator's trace feature.
To Illustrator, white is the same as transparent. It sees them the same.
When tracing, if you don't ignore white, then white objects are created for both white and transparent areas. If you do "ignore white" then no white objects are created - and since transparent is the ...
I have a need to be able to autosize text in a paragraph box to fit a specific height, and have been pulling my hair out trying to figure out how to do this. Using expressions and the scale property to fit the text is not a good solution for me. It would be really nice if Adobe had a way to easily tell if text in a paragraph text box was overflowing the box.