When I print using self-weeding transfer paper, the image doesn’t weed properly leaving a halo the size of the entire film.
Why is that happening?
With self-weeding transfer paper for light-coloured fabrics, used on fabric obviously, the issue you mention can occur if the combination of time, temperature and pressure is excessive.
I suggest trying to reduce one of these variables at a time (start with the pressure, then reduce the temperature, then the time) and see what happens.
With laser transfer paper for solid materials (used on metal, of course), this issue has never occurred, as it is really difficult to create halos on a solid surface.
But if it does happen, the same method described above should be used.