I don't have as much experience as most of the posters here, but I would think that your last statement is right on target, white bobbin thread just more prominent on black fabric. I think I would use black embroidery thread on the bobbin instead of the white bobbin thread.

When you do regular sewing on the Platinum, do you have the option to adjust the upper and lower tension? If so, then you can reduce the tension while embroidering...your upper tension is a bit too tight, so reduce it a snudge. Other thought is to float some more stabilizer underneath to keep the bobbin thread from popping through.

There are different weights of bobbin thread and embroidery thread so I don't see how the platinum can tell what is going through the machine...it's a machine. It's up to the human operator to find the right combination of thread and stabilizer.

I've wound the embroidery thread on the bobbin for 3-dimensional work and lace. Works like a charm. Also a perfect color match of course.

I would wind a black bobbin w/embroidery thread as well if you can't adjust your tension. Also, if you have fabric markers, you can touch up with those. If not, a black sharpie will work great too.

I am agree with stitchntime9, A better way is use blk bobbin thread.

Here is a link that might be useful: Atomic Embroidery Digitizing

I agree, use your top embroidery thread in the bobbin. Works well for me, especially on lace. The poly thread I use (Isacord) is fairly expensive, tho, so it's a good idea to get some 60 weight bobbin threads in basic colors when you get a chance. I get my white bobbin thread on a big cone and the colors in smaller spools. But sometimes you just can't match the colors...then use the top thread.