@jonny_firebrand. I had this problem too. Dan’s tip to me is in the last paragraph of this quote from my June 11th post:
https://community.glowforge.com/t/wjls-production-machine-projects/8550/54?u=bill_laba.
Try ctrl-shift-arrow to control fill in of shapes. It worked back in June, hopefully will still do so. I don’t have time to try it right now.
For the batman scan, did you try changing the contrast? I think you hold ctrl and hit up or down to change the contrast of the image after you scan it.
Thanks @joe. I thought I remembered that there was a way to adjust contrast. Looked at all the commands on screen and couldn’t find it. The control-arrow shortcut does change the contrast, but unfortunately the contrast difference was way too much on this scan. If I adjusted enough to start to fill the interior void, the rest of the graphic started to fill also. I have written this down for future use. It already could have come handy for the Batman linocut in this post. We adjusted contrast outside of the 
's interface to compensate for it being a black and beige image. As you’ll see in one of the posts above, Geordi did come up with an alternative fix and the Batman/Joker coaster is complete. The Romulan/Enterprise coaster is about 6 minutes from completion.
There’s another even secret-er shortcut - I believe it’s ctrl-shift-arrow. It’s in the manual. It controls the amount of “fill in” of shapes. It’s hard to explain but very useful to experiment with.