Almost always one of two things, and neither is a bug:
1. Wrong rotation axis. Spin the model around its longest, most-detailed axis. The import pop-up now recommends one for you (Vertical for tall shapes, Horizontal for long shapes lying down), but double-check it. The wrong axis means the silhouettes barely change as the model turns, so the hull stays vague. Re-import and try the other axis — it can be night and day.
2. Too few angles. More angles = a tighter hull. 12 is a good start; bump to 24 if you still see facets. Past ~24–36 it barely changes for most shapes.
And remember the hard limit: anything the wire can't see from outside in some silhouette (interior pockets, hidden concavities) will fill in. That's the nature of hot-wire cutting, not a fault in the tool. Turn on Show original (ghost) (under the viewer) to overlay your model on the result and see exactly what's reproduced vs filled.
1. Wrong rotation axis. Spin the model around its longest, most-detailed axis. The import pop-up now recommends one for you (Vertical for tall shapes, Horizontal for long shapes lying down), but double-check it. The wrong axis means the silhouettes barely change as the model turns, so the hull stays vague. Re-import and try the other axis — it can be night and day.
2. Too few angles. More angles = a tighter hull. 12 is a good start; bump to 24 if you still see facets. Past ~24–36 it barely changes for most shapes.
And remember the hard limit: anything the wire can't see from outside in some silhouette (interior pockets, hidden concavities) will fill in. That's the nature of hot-wire cutting, not a fault in the tool. Turn on Show original (ghost) (under the viewer) to overlay your model on the result and see exactly what's reproduced vs filled.