Hi,
It’s really not documented correctly. Please try this:
lv_obj_set_style_pad_column(chart, 0, LV_PART_ITEMS); /*Space between columns of the same index*/
lv_obj_set_style_pad_column(chart, 0, LV_PART_MAIN); /*Space between columns of the adjacent index*/
If it works well for you, I’ll update the docs.