Short answer, right click on the outside line in the white areas until all the white is gone. Also try the Automatic > Create objects/paths function that I mentioned in my last post (ESTLcam won't let me select carve side - #5 by dalrun). As orob said, you’ll likely want to to add a Pocketing tool (and set a depth limit).
All drawing shapes are best closed/fixed in the drawing program, but some issues/leaking can be bypassed using the manual path setting option.
There are examples of most of the above in Christians carving video (https://youtu.be/hHdiHjDC-mQ) which is reasonably easy to follow with automatically translated subtitles.