When I change it to show in the GUI but not on belts, it leaves a trail of images where belts used to be. I can run more tests if you need more timing details.
Happens in Nullius.
The images are from the item's image, not the letters. Eg in Nullius, the red science flask has a gear superimposed over it. This gear remains, but not the flask. Another time, actual sandstone ore remained.