Starch test with iodine.

Theory

The effect is only seen when both iodine as an element and iodide as an ion are present.  Iodine, together with the iodide ion, forms a complex which dissolves in water, unlike iodine on its own. Molecular iodine (I2) reacts with iodide (I-) which is a negatively charged ion and creates an anion (I3-). The anion dissolves easily in water (which is polar). 

Question

So this test will work with Lugol reagent, because it have molecular iodine and potassium iodide, this will create the anion (I3-) that causes the change of color in the starch. If the test is performed with Betadine (Povidone-Iodine) in theory wont work, because only molecular iodine is present, but in the practice, betadine will cause the change of color in the starch, how is this possible? Need a chemical explanation.